Python 3.8.2 : Create a Django Calendar - part 001.

This tutorial show you how can use pipenv tool and set the Django project in order to create a calendar with Django project.

First, install the pipenv tool using the pip tool:

python -m pip install pipenv
Collecting pipenv
...
Successfully installed pipenv-2020.6.2 virtualenv-clone-0.5.4

You can see all options and features with this command:

pipenv
Usage: pipenv [OPTIONS] COMMAND [ARGS]...

Options:
  --where                         Output project home information.
  --venv                          Output virtualenv information.
  --py                            Output Python interpreter information.
  --envs                          Output Environment Variable options.
  --rm                            Remove the virtualenv.
  --bare                          Minimal output.
  --completion                    Output completion (to be executed by the
                                  shell).

  --man                           Display manpage.
  --support                       Output diagnostic information for use in
                                  GitHub issues.

  --site-packages / --no-site-packages
                                  Enable site-packages for the virtualenv.
                                  [env var: PIPENV_SITE_PACKAGES]

  --python TEXT                   Specify which version of Python virtualenv
                                  should use.

  --three / --two                 Use Python 3/2 when creating virtualenv.
  --clear                         Clears caches (pipenv, pip, and pip-tools).
                                  [env var: PIPENV_CLEAR]

  -v, --verbose                   Verbose mode.
  --pypi-mirror TEXT              Specify a PyPI mirror.
  --version                       Show the version and exit.
  -h, --help                      Show this message and exit.


Usage Examples:
   Create a new project using Python 3.7, specifically:
   $ pipenv --python 3.7

   Remove project virtualenv (inferred from current directory):
   $ pipenv --rm

   Install all dependencies for a project (including dev):
   $ pipenv install --dev

   Create a lockfile containing pre-releases:
   $ pipenv lock --pre

   Show a graph of your installed dependencies:
   $ pipenv graph

   Check your installed dependencies for security vulnerabilities:
   $ pipenv check

   Install a local setup.py into your virtual environment/Pipfile:
   $ pipenv install -e .

   Use a lower-level pip command:
   $ pipenv run pip freeze

Commands:
  check      Checks for PyUp Safety security vulnerabilities and against PEP
             508 markers provided in Pipfile.

  clean      Uninstalls all packages not specified in Pipfile.lock.
  graph      Displays currently-installed dependency graph information.
  install    Installs provided packages and adds them to Pipfile, or (if no
             packages are given), installs all packages from Pipfile.

  lock       Generates Pipfile.lock.
  open       View a given module in your editor.
  run        Spawns a command installed into the virtualenv.
  shell      Spawns a shell within the virtualenv.
  sync       Installs all packages specified in Pipfile.lock.
  uninstall  Uninstalls a provided package and removes it from Pipfile.
  update     Runs lock, then sync.

Create a folder for your project, I used this folder named django_test_002:

mkdir django_test_002

Create a virtualenv using the pipenv shell

django_test_002>pipenv shell
Creating a virtualenv for this project…
Pipfile: D:\Projects\Python\django_test_002\Pipfile
Using D:/Python38/python.exe (3.8.2) to create virtualenv…
...

Install Django python package:

(django_test_002-bp-hUvnN) D:\Projects\Python\django_test_002> pipenv install Django
Installing Django…
Adding Django to Pipfile's [packages]…
Installation Succeeded
Pipfile.lock not found, creating…
Locking [dev-packages] dependencies…
Locking [packages] dependencies…
 Locking...Building requirements...
Resolving dependencies...
Success!
Updated Pipfile.lock (a6086c)!
Installing dependencies from Pipfile.lock (a6086c)…
  ================================ 0/0 - 00:00:00

Let's test the pipenv shell tool with a simple example for activate, deactivate and exit:

D:\Projects\Python\django_test_002>pipenv shell
Launching subshell in virtual environment…
Microsoft Windows [Version 10.0.18363.900]
(c) 2019 Microsoft Corporation. All rights reserved.

(django_test_002-bp-hUvnN) D:\Projects\Python\django_test_002>activate

(django_test_002) (django_test_002-bp-hUvnN) D:\Projects\Python\django_test_002>deactivate
(django_test_002-bp-hUvnN) D:\Projects\Python\django_test_002>exit

Stores all the python packages you installed into a requirements.txt file

D:\Projects\Python\django_test_002>pipenv shell
Launching subshell in virtual environment…
Microsoft Windows [Version 10.0.18363.900]
(c) 2019 Microsoft Corporation. All rights reserved.

(django_test_002-bp-hUvnN) D:\Projects\Python\django_test_002>pip3 freeze > requirements.txt

Create django project named test_calendar:

(django_test_002-bp-hUvnN) D:\Projects\Python\django_test_002>django-admin startproject test_calendar

Start server to check that our project is running at localhost:8000.

(django_test_002-bp-hUvnN) D:\Projects\Python\django_test_002>cd test_calendar

(django_test_002-bp-hUvnN) D:\Projects\Python\django_test_002\test_calendar>python manage.py runserver
Watching for file changes with StatReloader
Performing system checks...

System check identified no issues (0 silenced).

You have 17 unapplied migration(s). Your project may not work properly until you apply the migrations 
for app(s): admin, auth, contenttypes, sessions.
Run 'python manage.py migrate' to apply them.
June 13, 2020 - 20:52:00
Django version 3.0.7, using settings 'test_calendar.settings'
Starting development server at http://127.0.0.1:8000/
Quit the server with CTRL-BREAK.

Now, you can open with your browser the default link http://127.0.0.1:8000/ and you will see the start page of Django framework.

Use Ctrl+C keys to stop it, and create an application.

I used the next command to create first_calendar application.

D:\Projects\Python\django_test_002\test_calendar>python manage.py startapp first_calendar

Into the folder application first_calendar make these changes to views.py from to create a index view:

from django.shortcuts import render
from django.http import HttpResponse

# Create your views here.

def index(request):
    return HttpResponse('hello')

Create a new file named urls.py in the folder first_calendar and add this source code:

from django.conf.urls import url
from . import views

app_name = 'first_calendar'
urlpatterns = [
    #url(r'^index/$', views.index, name='index'),
    url('', views.index,  name='index'),
]

Return to the project base folder and add the view to urls.py from the project test_calendar folder:

from django.contrib import admin
from django.urls import path, include

urlpatterns = [
    path('admin/', admin.site.urls),
    path('', include('first_calendar.urls')),
]

Into the project folder test_calendar add the application to the file settings.py.

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'first_calendar',
]

Use migrate option to migrate the project:

(django_test_002-bp-hUvnN) D:\Projects\Python\django_test_002\test_calendar>python manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, sessions
Running migrations:
  Applying contenttypes.0001_initial... OK
  Applying auth.0001_initial... OK
  Applying admin.0001_initial... OK
  Applying admin.0002_logentry_remove_auto_add... OK
  Applying admin.0003_logentry_add_action_flag_choices... OK
  Applying contenttypes.0002_remove_content_type_name... OK
  Applying auth.0002_alter_permission_name_max_length... OK
  Applying auth.0003_alter_user_email_max_length... OK
  Applying auth.0004_alter_user_username_opts... OK
  Applying auth.0005_alter_user_last_login_null... OK
  Applying auth.0006_require_contenttypes_0002... OK
  Applying auth.0007_alter_validators_add_error_messages... OK
  Applying auth.0008_alter_user_username_max_length... OK
  Applying auth.0009_alter_user_last_name_max_length... OK
  Applying auth.0010_alter_group_name_max_length... OK
  Applying auth.0011_update_proxy_permissions... OK
  Applying sessions.0001_initial... OK

Go back to default project folder. Now you can test using this command:

(django_test_002-bp-hUvnN) D:\Projects\Python\django_test_002\test_calendar>python manage.py runserver
Watching for file changes with StatReloader
Performing system checks...

System check identified no issues (0 silenced).
June 13, 2020 - 21:52:42
Django version 3.0.7, using settings 'test_calendar.settings'
Starting development server at http://127.0.0.1:8000/
Quit the server with CTRL-BREAK.

You will see a simple word: hello. Let's fix the admin login by adding user:

python manage.py createsuperuser
Username (leave blank to use 'catal'): catafest
Email address: catafest@yahoo.com
Password:

I set user catafest and password admin76 and then use the next command to see the result on http://127.0.0.1:8000/admin:

python manage.py runserver

The next step is to create a Event class into models.py file from first_calendar:

from django.db import models

class Event(models.Model):
    title = models.CharField(max_length=200)
    description = models.TextField()
    start_time = models.DateTimeField()
    end_time = models.DateTimeField()

Then add this class into admin.py file:

from django.contrib import admin
from first_calendar.models import Event

admin.site.register(Event)

This tutorial set the one default Django project with the Django framework version 3.0.7 .

Python 3.8.3 : Using the fabric python module - part 002.

This is second tutorial about the fabric.

Using the old example, I will show you how can use it with some basic features.

The example cover these issues:

• show fabric version;
• use task decorator;
• import and use multiple hosts;

The documentation page come with this info about task:

Fabric 1.1 introduced the Task class to facilitate new features and enable some programming best practices, specifically:

  Object-oriented tasks. Inheritance and all that comes with it can make for much more sensible code reuse than passing around simple function objects. The classic style of task declaration didn’t entirely rule this out, but it also didn’t make it terribly easy.

  Namespaces. Having an explicit method of declaring tasks makes it easier to set up recursive namespaces without e.g. polluting your task list with the contents of Python’s os module (which would show up as valid “tasks” under the classic methodology.)

With the introduction of Task, there are two ways to set up new tasks:

 Decorate a regular module level function with @task, which transparently wraps the function in a Task subclass. The function name will be used as the task name when invoking.

 Subclass Task (Task itself is intended to be abstract), define a run method, and instantiate your subclass at module level. Instances’ name attributes are used as the task name; if omitted the instance’s variable name will be used instead.

Let's see the example:

import fabric
from fabric import Connection
print("fabric.__version__")
print(fabric.__version__)

print("fabric.__version_info__")
print(fabric.__version_info__)

print("dir(fabric)")
print(dir(fabric))

import getpass
host = "catafest@tty.sdf.org"
password = getpass.getpass('Password for SDF account:')
with Connection("catafest@tty.sdf.org", connect_kwargs={"password":password}) as con:
    print("I will run command: ls")
    con.run("ls")
    
# using the task decorator 
from fabric import task
@task    
def processes(con):
    return con.run("ps -aux", hide = True).stdout.strip()

# print processes
print(processes(con))
con.run("exit")
# use the import for multiple host with all modules

from fabric import Connection, Config, SerialGroup, ThreadingGroup, exceptions, runners
from fabric.exceptions import GroupException

hosts = "catafest@tty.sdf.org,catafest@tty.sdf.org"

def testHosts(hosts):
    # Get list of hosts from somewhere, and convert them to connections
    hosts = hosts.split(",")
    servers = [Connection(host=host,connect_kwargs={"password":password}) for host in hosts]
    thread_group = ThreadingGroup.from_connections(servers)
    results = thread_group.run("who -a", hide=True)
    for r in results:
        connection = results[r]
        return connection.stdout.strip() 
        
print(testHosts(hosts))

The result of this python script:

fabric.__version__
2.5.0
fabric.__version_info__
(2, 5, 0)
dir(fabric)
['Config', 'Connection', 'Executor', 'Group', 'GroupResult', 'Remote', 'Result', 'SerialGroup', 'Task', 
'ThreadingGroup', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', 
'__package__', '__path__', '__spec__', '__version__', '__version_info__', '_version', 'config', 'connection', 
'exceptions', 'executor', 'group', 'runners', 'task', 'tasks', 'transfer', 'tunnels', 'util']
Password for SDF account:
I will run command: ls
USER            PID %CPU %MEM    VSZ    RSS TTY     STAT STARTED     TIME COMMAND
...
catafest      10431  0.0  0.0  30496   3120 ?       S     5:50PM  0:00.00 sshd:
...
catafest      19243  0.0  0.0  12008   1096 ?       O     5:50PM  0:00.00 ps -a
...
user   pts/0    Jun  7 17:40 00:10         0  term=0 exit=0 sess=0 type=user process  ...

Python 3.8.3 : Using the fabric python module - part 001.

The tutorial for today is about fabric python module.

You can read about this python module on the official webpage.

The team comes with this intro:

Fabric is a high level Python (2.7, 3.4+) library designed to execute shell commands remotely over SSH, yielding useful Python objects in return

...

It builds on top of Invoke (subprocess command execution and command-line features) and Paramiko (SSH protocol implementation), extending their APIs to complement one another and provide additional functionality.

I used python version 3.8.3rc1 to install with the pip3 tool.

pip3 install fabric
Collecting fabric
...
Installing collected packages: invoke, fabric
Successfully installed fabric-2.5.0 invoke-1.4.1

from fabric import Connection
import getpass
host = "catafest@tty.sdf.org"
password = getpass.getpass('Password for SDF account:')
with Connection("catafest@tty.sdf.org", connect_kwargs={"password":password}) as con:
    print("I will run command: id -u -n")
    con.run("id -u -n")
    print("I will run command: df -h")
    con.run("df -h")
    print("I will run command for SDF help: help")
    con.run("help")
    out = con.run("free")
    print("output for dir(out)")
    print(dir(out))
    print("output for out.shell")
    print(out.shell)
    print("output for out.connection")
    print(out.connection)
    print("output for out.stdout")
    print(out.stdout)
    print("output for out.env")
    print(out.env)

This is a simple example tested on my SDF account.

About the SDF:

The Super Dimension Fortress is a networked community of free software
authors, teachers, librarians, students, researchers, hobbyists,
computer enthusiasts, the aural and visually impaired. It is operated
as a recognized non-profit 501(c)(7) and is supported by its members.

Our mission is to provide remotely accessible computing facilities for
the advancement of public education, cultural enrichment, scientific
research and recreation. Members can interact electronically with each
other regardless of their location using passive or interactive forums.
Further purposes include the recreational exchange of information
concerning the Liberal and Fine Arts.

Members have UNIX shell access to games, email, usenet, chat, bboard,
webspace, gopherspace, programming utilities, archivers, browsers, and
more. The SDF community is made up of caring, highly skilled people who
operate behind the scenes to maintain a non-commercial INTERNET.

For information about membership levels, click on 'join' above.

Let see my example:

python fabric_001.py
Password for SDF account:
I will run command: id -u -n
catafest
I will run command: df -h
Filesystem         Size       Used      Avail %Cap Mounted on
/dev/wd0a           35G       2.0G        31G   6% /
nol1:/sdf           23T       5.1T        17T  23% /sdf
ptyfs              1.0K       1.0K         0B 100% /dev/pts
I will run command for SDF help: help
tput: No terminal type specified and no TERM variable set in the environment.
SDF Help System - v8, 1993 - sdf!smj

 [a] Directory and File Utilities
 [b] Email Information
 [c] USENET Information
 [d] User and Process Information
 [e] Tutorials and Very Useful Commands
 [f] ARPA Services (internetworking)
 [g] Homepage, VHOST and MetaARPA Utilities

 [q] Quit SDF Help System

Your Choice? q
q
For more help, type 'faq'
For a list of basic UNIX commands, type 'unix'
For live help, type 'helpdesk'

             total       used       free    buffers
Mem:      16274580   15098664    1175916   13433820
Swap:      1049292          0    1049292
output for dir(out)
['__bool__', '__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', 
'__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', 
'__ne__', '__new__', '__nonzero__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', 
'__str__', '__subclasshook__', '__weakref__', 'command', 'connection', 'encoding', 'env', 'exited', 'failed', 
'hide', 'ok', 'pty', 'return_code', 'shell', 'stderr', 'stdout', 'tail']
output for out.shell
C:\Windows\system32\cmd.exe
output for out.connection
<Connection host=tty.sdf.org user=catafest>
output for out.stdout
             total       used       free    buffers
Mem:      16274580   15098664    1175916   13433820
Swap:      1049292          0    1049292

output for out.env
{}

Python Qt5 : PyQt5 and PyGame compatibility with source code.

This tutorial tries to solve from the objectives related to solving and stabilizing compatibility errors between PyQt4 and PyQt5 and creating a common interface between PyQt5 and PyGame.

There is always the same problem in programming when the developer for some reason has to change classes, methods and functions and reusing the old code is no longer valid.

In this case, common or other errors occur, which leads to a waste of time.

I will present a simple way to solve these problems.

I really like to use the PyQt5 module to create interfaces for my python programs and scripts.

Like any programmer who hasn't fully used all A.P.I, I always use the old source code I programmed in the past.

What the developer says about the transition from PyQt4 to PyQt5 we can see on the official page.

Obviously, you will have to move on to things to know but it is quite difficult to always come back and read this content when you have programming errors.

Today, I wanted to make a simple drawing interface in PyGame that would be included in a PyQt5 interface.

I tried to use an old code created by me in PyQt4 but I realized that I had encountered errors before switching to the new PyQt5.

This compatibility problem generates errors and can be solved as follows: by knowing the exact solution and fixing errors in real time, studying the changes created by the developer or the classic search for errors.

My solution comes with the help of these solutions and requires a simple step using the commented source code.

To show you how simple it is to understand I will show you the source code for the interface I built that simply to solves the problem of understanding compatibility by reading the developer source code with simple and useful comments.

#the old import for PyQt4
#from PyQt4 import QtGui

#the new import for PyQt5
#from PyQt5 import QtCore, QtGui, QtWidgets
#class MainWindow(QtWidgets.QMainWindow, UI.MainUI.Ui_MainWindow):

from PyQt5 import QtGui
from PyQt5 import QtWidgets
import pygame
import sys

# old definition for PyQt4 for QWidget
#class ImageWidget(QtGui.QWidget):
class ImageWidget(QtWidgets.QWidget):   
    def __init__(self,surface,parent=None):
        super(ImageWidget,self).__init__(parent)
        w=surface.get_width()
        h=surface.get_height()
        self.data=surface.get_buffer().raw
        self.image=QtGui.QImage(self.data,w,h,QtGui.QImage.Format_RGB32)

    def paintEvent(self,event):
        my_paint=QtGui.QPainter()
        # the definitions for PyQt4 and PyQt5 use QtGui.QPainter()     
        my_paint.begin(self)
        my_paint.drawImage(0,0,self.image)
        my_paint.end()
        
# old definition for PyQt4 for QMainWindow
#class MainWindow(QtGui.QMainWindow):
class MainWindow(QtWidgets.QMainWindow):
    def __init__(self,surface,parent=None):
        super(MainWindow,self).__init__(parent)
        self.setFixedSize(640, 480)
        self.setCentralWidget(ImageWidget(surface))
# this part of source code need to be updated if you want to use animation        
# init PyGame 
pygame.init()
# define a surface 
my_surface=pygame.Surface((640,480))
# fill the surface, see https://www.pygame.org/docs/ref/surface.html#pygame.Surface.fill
my_surface.fill((0,0,255,176))
# draw circle see https://www.pygame.org/docs/ref/draw.html#pygame.draw.circle
pygame.draw.circle(my_surface,(0,0,127,255),(76,76),76)
# draw ellipse (surface, color(R,G,B), size (x,y,x+dx, y+y+dy) )
pygame.draw.ellipse(my_surface,(127,0,0,0),(0,0,12,76))
 
# this part of source code will show 
# the my_surface created with PyGame in PyQt5
# old definition for PyQt4
#app=QtGui.QApplication(sys.argv)
app=QtWidgets.QApplication(sys.argv)
my_window=MainWindow(my_surface)
my_window.show()
app.exec_()

Python 3.8.3 : A brief introduction to the Celery python package.

The development team tells us:

Celery is a simple, flexible, and reliable distributed system to process vast amounts of messages, while providing operations with the tools required to maintain such a system.

To do that Celery uses tasks.

These task queues are used as a mechanism to distribute work across threads or machines using brokers.

A task a client puts a message on the queue and the broker then delivers the message to a worker.

The install of this python package is simple:

Celery can run on a single machine, on multiple machines, or even across datacenters.

pip3 install -U Celery
Collecting Celery
...
Installing collected packages: pytz, billiard, vine, amqp, kombu, Celery
Successfully installed Celery-4.4.2 amqp-2.5.2 billiard-3.6.3.0 kombu-4.6.8 pytz-2020.1 vine-1.3.0

The Celery library must be instantiated before use like an application.

First, I tested with a simple example application from the official website.

from celery import Celery
app = Celery()

@app.task
def add(x, y): return x + y

if __name__ == '__main__':
    app.worker_main()

When I run it this application the output is this:

python.exe .\example_tasks.py
 
 -------------- celery@DESKTOP-9DSLSMF v4.4.2 (cliffs)
--- ***** ----- 
-- ******* ---- Windows-10-10.0.18362-SP0 2020-05-24 18:30:04
- *** --- * --- 
- ** ---------- [config]
- ** ---------- .> app:         __main__:0x1c697187940
- ** ---------- .> transport:   amqp://guest:**@localhost:5672//
- ** ---------- .> results:     disabled://
- *** --- * --- .> concurrency: 6 (prefork)
                .> celery           exchange=celery(direct) key=celery


[2020-05-24 18:30:06,273: ERROR/MainProcess] consumer: Cannot connect to amqp://guest:**@127.0.0.1:5672//:
[WinError 10061] No connection could be made because the target machine actively refused it.
Trying again in 2.00 seconds... (1/100)

[2020-05-24 18:30:10,296: ERROR/MainProcess] consumer: Cannot connect to amqp://guest:**@127.0.0.1:5672//:
[WinError 10061] No connection could be made because the target machine actively refused it.
Trying again in 4.00 seconds... (2/100)

[2020-05-24 18:30:16,323: ERROR/MainProcess] consumer: Cannot connect to amqp://guest:**@127.0.0.1:5672//:
[WinError 10061] No connection could be made because the target machine actively refused it.
Trying again in 6.00 seconds... (3/100)


worker: Hitting Ctrl+C again will terminate all running tasks!

worker: Warm shutdown (MainProcess)

This error is show because I trying to connect to a local instance of default broker named RabbitMQ .

RabbitMQ is most popular open source message broker and can be download it from the official webpage.

If you want to install RabbitMQ, then you need to install Erlang, see screenshot:

This is not the only one option, you have many features like for example Redis.

The development team try experimental support for a myriad of other solutions, including using SQLite for local development.

A full list with all supported brokers can be found here.

Celery is easy to integrate with web frameworks, some of them even have integration packages:

• Pyramid  with pyramid_celery;
• Pylons with celery-pylons;
• Flask not needed;
• web2py with web2py-celery;
• Tornado with tornado-celery;
• Tryton with celery_tryton;
• and Django also no not needed because works well.
  

Maybe I will make another tutorial about this python module and how works with Redis or Django.

News : Microsoft Build digital event for Python users.

We in the Python team are excited to be joining Microsoft Build 2020, which is starting next Tuesday, May 19. During a global pandemic, Build has turned into a digital-only event, running for 48 continuous hours, that is open to anyone around the world, at no cost.

At Build, we’ll demo the new capabilities we’ve been building recently. We’ll also showcase the work we have been doing to enable Python developers to build applications and analyze data using Visual Studio Code. Lastly, we’ll show how you can run Python web apps and machine learning models on the cloud with Azure.

Our friends across Microsoft will also present services and tools that developers, including those working with Python, can leverage to remain productive and continue collaborating even in remote, distributed teams.

You can participate in a live Q&A stream session:

• Tuesday May 19 at 9pm
• Wednesday May 20 at 12:30pm
• Thursday May 21 at 3am

This event can be found at the official webpage.

Python 3.8.3 : Simple example to fix maximum recursion depth exceeded.

This short tutorial try to solve simple and easy the stack limit for recursion without using advanced programming techniques.

sys.setrecursionlimit(limit)
    Set the maximum depth of the Python interpreter stack to limit. 
This limit prevents infinite recursion from causing an overflow of the C stack 
and crashing Python.

This can be done in most cases with:

import sys
sys.setrecursionlimit(1976)

Let's test with an simple example for a given number.

input_number = 1234567890987654321

I create a script for the next function to print the result:

def split_input(n):
    return split_input(n // 10) + [n % 10]

The result of this function is:

python flow_001.py
Traceback (most recent call last):
  File "flow_001.py", line 12, in 
    input_list = split_input(input_number)
  File "flow_001.py", line 10, in split_input
    return split_input(n // 10) + [n % 10]
  File "flow_001.py", line 10, in split_input
    return split_input(n // 10) + [n % 10]
  File "flow_001.py", line 10, in split_input
    return split_input(n // 10) + [n % 10]
  [Previous line repeated 996 more times]
RecursionError: maximum recursion depth exceeded

You can see I got an error. Let fix this function with a proper source code:

def split_nr(n):
    if n < 1:
        return [n]
    else:
        return split_nr(n // 10) + [n % 10] 

This will solve the recursion split function.

python flow_001.py
[1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 9, 8, 7, 6, 5, 4, 3, 2, 1]

IronPython 2.7.7 : Intro on RevitPythonShell.

This is one of the several ways to use RevitPythonWrapper:

• pyRevit;
• RevitPythonShell;
• Dynamo;

This tool help you to use python with the Revit tool and can be found at the GitHub webpage.

They say:
The RevitPythonShell adds an IronPython interpreter to Autodesk Revit and Vasari. The RevitPythonShell (RPS) lets you to write plugins for Revit in Python, my favourite scripting language! But even better, it provides you with an interactive shell that lets you see the results of your code as you type it. This is great for exploring the Revit API while writing your Revit Addins - use this in combination with the RevitLookup database exploration tool to become a Revit API Ninja :)
You need to install your instaler according with the Revit version.
You can start it from Main Menu - Add-Ins and you see it.
Is very easy to use it, let's see one simple example:

import clr
clr.AddReference("RevitAPI")
from Autodesk.Revit.DB import BuiltInCategory as Bic
from Autodesk.Revit.DB import FilteredElementCollector as Fec
from Autodesk.Revit.DB import Transaction
# reference to the current open revit model is
doc = __revit__.ActiveUIDocument.Document

Let's see a simple example on Revit with an wall and a simple door.

IronPython 2.7.7 (2.7.7.0) on .NET 4.0.30319.42000 (64-bit)
Type "help", "copyright", "credits" or "license" for more information.
>>> a = b = 1 
>>> c = a + b + 1
>>> print(c)
3
>>> from Autodesk.Revit.DB import FilteredElementCollector as Fec
>>> from Autodesk.Revit.DB import BuiltInCategory as Bic
>>> doors = Fec(doc).OfCategory(Bic.OST_Doors).WhereElementIsNotElementType().ToElements()
>>> print(dir(doors))
['Add', 'AddRange', 'AsReadOnly', 'BinarySearch', 'Capacity', 'Clear', 'Contains', 'ConvertAll', 'CopyTo',
'Count', 'Enumerator', 'Equals', 'Exists', 'Find', 'FindAll', 'FindIndex', 'FindLast', 'FindLastIndex', 
'ForEach', 'GetEnumerator', 'GetHashCode', 'GetRange', 'GetType', 'IndexOf', 'Insert', 'InsertRange', 
'IsReadOnly', 'IsSynchronized', 'Item', 'LastIndexOf', 'MemberwiseClone', 'ReferenceEquals', 'Remove', 
'RemoveAll', 'RemoveAt', 'RemoveRange', 'Reverse', 'Sort', 'SyncRoot', 'ToArray', 'ToString', 'TrimExcess', 
'TrueForAll', '__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__format__', 
'__getattribute__', '__getitem__', '__hash__', '__init__', '__iter__', '__len__', '__new__', 
'__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__setitem__', '__sizeof__', 
'__str__', '__subclasshook__']
>>> for each_door in doors:
... 	print(each_door.Id)
... 	print(each_door.Mirrored)
... 	print(each_door.Symbol.LookupParameter("Type Name").ToString())
... 
840590
False
Autodesk.Revit.DB.Parameter
>>> 

Let's see the output of this code on Revit.

Python 3.8.3 : Pyxel free game engine.

Pyxel is a free game engine is build for create old fashioned pixel art style games easily.
Pyxel is published under MIT License.
This allow you to use 2D sprites, sound and interactions.
The project can be found at the GitHub webpage.
The basic features are:

• Run on Windows, Mac, and Linux
• Code writing with Python3
• Fixed 16 color palette
• 256x256 sized 3 image banks
• 256x256 sized 8 tilemaps
• 4 channels with 64 definable sounds
• 8 musics which can combine arbitrary sounds
• Keyboard, mouse, and gamepad inputs
• Image and sound editor

The instalation is easy.

pip3 install pyxel
Collecting pyxel
...
Successfully installed altgraph-0.17 pefile-2019.4.18 pyinstaller-3.6 pywin32-ctypes-0.2.0 pyxel-1.3.7

Use this command to start the tool for create sprites and sounds.

pyxeleditor

You can test many examples on GitHub.
The basic example from the web is simple:

import pyxel

class App:
    def __init__(self):
        pyxel.init(160, 120, caption="Hello Pyxel")
        pyxel.image(0).load(0, 0, "assets/pyxel_logo_38x16.png")
        pyxel.run(self.update, self.draw)

    def update(self):
        if pyxel.btnp(pyxel.KEY_Q):
            pyxel.quit()

    def draw(self):
        pyxel.cls(0)
        pyxel.text(55, 41, "Hello, Pyxel!", pyxel.frame_count % 16)
        pyxel.blt(61, 66, 0, 0, 0, 38, 16)

App()

I start with a simple example. I don't find a collision system on Pyxel. Let's see the source code:

import pyxel
from pyxel import circ, cls, flip, init
from random import randint

# the position of the ball
x = y = 30  
# the speed of the ball
v = w = 3  
# create the screen as 160x120 size
pyxel.init(160, 112)  
#
data = [70, 60, 30, 70]


 # draw a line below the bar chart

while True:
    # erase the screen with color number 1 (blue)
    pyxel.cls(1)  

    # process the movement of the ball
    x += v
    y += w
    
    r = randint(0, 160)  
    a = randint(0, 112)
    rr = randint(0, 160) 
    aa = randint(0, 112)
    # create random lines on screen
    pyxel.line(a, aa, r, rr, 5)

    # set the border
    if x <= 7 or x >= 160:
        x = min(max(x, 7), 160)
        v = -v

    if y <= 7 or y >= 112:
        y = min(max(y, 7), 112)
        w = -w
  
    # draw the ball with different colors
    pyxel.circ(x, y, 4, pyxel.frame_count % 8) 
 
    # create a simple chart
    for i, d in enumerate(data):
        pyxel.rect(i * 33 + 10, 120 - d, 10, d, 8 + i) 

    # draw the game
    pyxel.flip()

Python 3.8.3 : Create shortcuts and add python to the context menu.

The tutorial for today is a simple script for python user.
If you run this python script in your folder you will get an python shortcut to the python and the python to the Context Menu in Windows 10.
The Context Menu can be used with right click from your mouse, see the screenshot.

This script can also be used with any executable if you make some changes.

import os
import pythoncom
from win32com.shell import shell

dirpath = os.getcwd()
if not os.path.exists(dirpath):
    os.makedirs(dirpath)

win_user = os.getenv('username')
shortcut_path = dirpath + r"\python.lnk"

shortcut_path = str(r"C:\\Users\\")+win_user+str("\\AppData\\Roaming\\Microsoft\\Windows\\SendTo\\python.lnk")

target_path = r"D:\\Python38_64\\python.exe"

shortcut_instance = pythoncom.CoCreateInstance(
    shell.CLSID_ShellLink, None, pythoncom.CLSCTX_INPROC_SERVER, shell.IID_IShellLink)
persist_file = shortcut_instance.QueryInterface(pythoncom.IID_IPersistFile)
shortcut_instance.SetPath(target_path)
persist_file.Save (shortcut_path, 0)

Python Qt5 : Simple text editor with QPlainTextEdit.

I haven't played python in a long time. It can be seen after the last article.
Today I installed Python 3.8.3 and my favorite PyQt5 and started to see how much I forgot from what I knew.
Installing PyQt5 python mode was simple.

pip3 install PyQt5
Collecting PyQt5
  Downloading PyQt5-5.14.2-5.14.2-cp35.cp36.cp37.cp38-none-win_amd64.whl (52.9 MB)
     |████████████████████████████████| 52.9 MB 80 kB/s
Collecting PyQt5-sip<13>=12.7
  Downloading PyQt5_sip-12.7.2-cp38-cp38-win_amd64.whl (59 kB)
     |████████████████████████████████| 59 kB 4.1 MB/s
Installing collected packages: PyQt5-sip, PyQt5
Successfully installed PyQt5-5.14.2 PyQt5-sip-12.7.2

The next step was to use QPlainTextEdit so the task was simple: an editor.
Because I created another article about a publisher, see this tutorial, I decided to attach a main menu with submenus and customize it.
The source code is simple to understand and is commented for a better understanding.

# -*- coding: utf-8 -*-
"""
@author: catafest
"""
import sys
import sys, os
from PyQt5 import QtCore, QtWidgets
from PyQt5.QtWidgets import QMainWindow, QAction, qApp, QApplication, QDesktopWidget
from PyQt5.QtWidgets import QMenu, QPlainTextEdit, QSizePolicy
from PyQt5.QtGui import QIcon
from PyQt5.QtCore import Qt,QSize

class Example(QMainWindow):
    #init the example class to draw the window application    
    def __init__(self, parent = None):
        super(Example,self).__init__(parent)  
        size_policy = self.sizePolicy()
        size_policy.setHeightForWidth(True)
        size_policy.setVerticalPolicy(QSizePolicy.Preferred)
        self.setSizePolicy(size_policy)  
        self.initUI()

    #create the def center to select the center of the screen         
    def center(self):
        # geometry of the main window
        qr = self.frameGeometry()
        
        # center point of screen
        cp = QDesktopWidget().availableGeometry().center()
        # move rectangle's center point to screen's center point
        qr.moveCenter(cp)
        # top left of rectangle becomes top left of window centering it
        self.move(qr.topLeft())

    #create the init UI to draw the application
    def initUI(self):               
        #create the action for the exit application with shortcut and icon
        #you can add new action for File menu and any actions you need
        #self.setMinimumSize(QSize(440, 240))    
        self.setWindowTitle("parse sensors output - catafest")
        self.editor_text = QPlainTextEdit(self)
        # font
        default_font = self.editor_text.font()
        default_font.setPointSize(9)
        self.editor_text.setFont(default_font)

        self.setCentralWidget(self.editor_text)
        #self.editor_text.setMinimumSize(400,600)

        self.editor_text.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAsNeeded)
        self.editor_text.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAsNeeded)
        
        self.editor_text.setObjectName("editor_text")
        self.editor_text.setEnabled(True)
        
        openAct = QAction(QIcon('open.png'), '&Open', self)        
        openAct.setShortcut('Ctrl+O')
        openAct.setStatusTip('Open file')
        openAct.triggered.connect(self.my_OpenDialog)

        exitAct = QAction(QIcon('exit.png'), '&Exit', self)        
        exitAct.setShortcut('Ctrl+Q')
        exitAct.setStatusTip('Exit application')
        exitAct.triggered.connect(qApp.quit)
        #create the status bar for menu 
        self.statusBar()
        #create the menu with the text File , add the exit action 
        #you can add many items on menu with actions for each item
        menubar = self.menuBar()
        fileMenu = menubar.addMenu('&File')
        # create open 
        fileMenu.addAction(openAct)
        # create exit 
        fileMenu.addAction(exitAct)
        
        # add submenu to menu 
        submenu = QMenu('Submenu',self)

        # some dummy actions
        submenu.addAction('Submenu 1')
        submenu.addAction('Submenu 2')
        
        # allow adding a sphere
        meshMenu = submenu.addMenu('Mesh')
        self.add_sphere_action = QAction('Add Sphere', self)
        self.add_sphere_action.triggered.connect(self.add_sphere)
        meshMenu.addAction(self.add_sphere_action)

        # add to the top menu
        menubar.addMenu(submenu)

        #layout = QtWidgets.QGridLayout(self)
        #layout.addWidget(self.editor_text)
        self.editor_text

        #resize the window application 
        self.resize(960, 720)
        #draw on center of the screen 
        self.center()
        #add title on windows application 
        self.setWindowTitle('Simple menu')
        #show the application
        self.show()
        #close the UI class

    def my_OpenDialog(self):
        path = QtWidgets.QFileDialog.getOpenFileName(
            self, 'Open file', '',
            'Text files (*.txt);;HTML files (*.html)')[0]
        if path:
            file = QtCore.QFile(path)
            if file.open(QtCore.QIODevice.ReadOnly):
                stream = QtCore.QTextStream(file)
                text = stream.readAll()
                info = QtCore.QFileInfo(path)
                if info.completeSuffix() == 'txt':
                    #self.editor_text.setHtml(text)
                    self.editor_text.insertPlainText(text)
                else:
                    self.editor_text.setPlainText(text)
                file.close()

    def add_sphere(self):
        """ add text with sphere """
        print("sphere")
        
if __name__ == '__main__':
    #create the application 
    app = QApplication(sys.argv)
    #use the UI with new  class
    ex = Example()
    #run the UI 
    sys.exit(app.exec_())

Python : Open any Jupiter notebook from GitHub in Colab.

In this tutorial I will show you how to open any Jupiter notebook from GitHub in the Google online Colab area.
First, go to the jupyter notebook in GitHub project.
Example:
https://github.com/catafest/colab_google/blob/master/catafest_001.ipynb
Change the link by adding the world tocolab after github, see the following example:
https://githubtocolab.com/catafest/colab_google/blob/master/catafest_001.ipynb
This will open the google colab notebook with the content of Jupiter notebook.
For more information about using Google Colab with GitHub, see this notebook from the Google Colab research.

Python 3.7.4 : A simple addon for Blender 3D version 2.8 .

Today I tested the python from Blender 3D software.
This software named Blender 3D come with python version 3.7.4 .
The version of this 3D tool is 2.82a .
This is a default addon with these python files: __init__.py , build.py, catafest_addon_start.py.
You can see a folder and images, but is not part of these tutorial.
The full source code of this addon can be found on my GitHub account on this project.
First python file named build.py will create the addon using this command:

python .\build.py

The source code for this python file is:

#!/usr/bin/env python

from os.path import abspath, dirname, join as pjoin
import zipfile

SRC_DIR = dirname(abspath(__file__))

with zipfile.ZipFile('catafest_addon_start.zip', 'w', zipfile.ZIP_DEFLATED) as arch:
    for filename in [
            '__init__.py',
            'catafest_addon_start.py',
            'textures/texture_001.png']:
        arch.write(pjoin(SRC_DIR, filename), 'add_mesh_catafest_blender_start/'+filename)

print('created file: catafest_addon_start.zip')

The next file named __init__.py will install the addon:

bl_info = {
    "name": "catafest addon start",
    "author": "Catalin George Festila",
    "license": "GPL",
    "version": (1, 1, 1),
    "blender": (2, 82, 0),
    "location": "View3D > Add > Mesh",
    "description": "Procedurally generate 3D catafest_addon_start from a random seed.",
    "warning": "",
    "wiki_url": "https://github.com/catafest/catafest_blender_start/blob/master/README.md",
    "tracker_url": "https://github.com/catafest/catafest_blender_start/issues",
    "category": "Add Mesh"
}

if "bpy" in locals():
    # reload logic (magic)
    import importlib
    importlib.reload(catafest_addon_start)
else:
    from . import catafest_addon_start

import bpy
from bpy.props import StringProperty, BoolProperty, IntProperty
from bpy.types import Operator

class Generate_catafest_mesh(Operator):
    """Procedurally generate a catafest 3D mesh from a random seed."""
    bl_idname = "mesh.generate_mesh"
    bl_label = "catafest_blender_start"
    bl_options = {'REGISTER', 'UNDO'}

    random_seed = StringProperty(default='', name='Seed')


    def execute(self, context):
        catafest_addon_start.generate_mesh(
            self.random_seed)
        return {'FINISHED'}

def menu_func(self, context):
    self.layout.operator(Generate_catafest_mesh.bl_idname, text="catafest_blender_start", icon="INFO")

def register():
    #bpy.utils.register_module(__name__)
    bpy.utils.register_class(Generate_catafest_mesh)
    #bpy.types.INFO_MT_mesh_add.append(menu_func)
    bpy.types.VIEW3D_MT_mesh_add.append(menu_func)

def unregister():
    #bpy.utils.unregister_module(__name__)
    bpy.utils.unregister_class(Generate_catafest_mesh)
    bpy.types.VIEW3D_MT_mesh_add.remove(menu_func)

if __name__ == "__main__":
    register()

The last one come with the addon features, for example to create a mesh.
This script will not create the mesh, but will show you how can be used, see generate_mesh.
You can change this generate_mesh to do your tasks.

# -*- coding:utf-8 -*-
#
# catafest_addon_start.py
#
# This is a Blender script that uses procedural generation to create
# a catafest 3D mesh from a random seed. Tested with Blender 2.77a.
#
# catalinfest@gmail.com
# https://github.com/catafest/catafest_blender_start
#
# ##### BEGIN GPL LICENSE BLOCK #####
#
#  This program is free software: you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation, either version 3 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program.  If not, see .
#  All rights reserved.
#
# ##### END GPL LICENSE BLOCK #####

# 

#import all python modules 
import sys
import os
import os.path
import bpy
import bmesh
import datetime
from math import sqrt, radians, pi, cos, sin
from mathutils import Vector, Matrix
from random import random, seed, uniform, randint, randrange
from enum import IntEnum
from colorsys import hls_to_rgb

DIR = os.path.dirname(os.path.abspath(__file__))

# get resource path
def resource_path(*path_components):
    return os.path.join(DIR, *path_components)

# Deletes all existing catafest_addon_start and unused materials from the scene
def reset_scene():
    for item in bpy.data.objects:
        item.select = item.name.startswith('catafest_addon_start')
    bpy.ops.object.delete()
    for material in bpy.data.materials:
        if not material.users:
            bpy.data.materials.remove(material)
    for texture in bpy.data.textures:
        if not texture.users:
            bpy.data.textures.remove(texture)
# Generate mesh            
def generate_mesh(random_seed=''):
    if random_seed:
        seed(random_seed)

    # Let's start with a unit BMesh cube scaled randomly
    bm = bmesh.new()
    bmesh.ops.create_cube(bm, size=1)

if __name__ == "__main__":
    
    reset_scene()
    for area in bpy.context.screen.areas:
        if area.type == 'VIEW_3D':
            ctx = bpy.context.copy()
            ctx['area'] = area
            ctx['region'] = area.regions[-1]
            bpy.ops.view3d.view_selected(ctx)
    
    scene = bpy.data.scenes["Scene"]
    scene.render.resolution_x = res_x
    scene.render.resolution_y = res_y
    scene.camera.rotation_mode = 'XYZ'
    scene.camera.data.angle = radians(fov)
    frame = 0
    timestamp = datetime.datetime.now().strftime('%Y%m%d_%H%M%S')