Friday, December 6, 2013

Start searching with python google module .

You can use python google module to start searching anything using this module.

First you need to install the python module using pip.

# pip install google
Downloading/unpacking google
  Downloading google-1.05.zip
  Running setup.py egg_info for package google
    
Requirement already satisfied (use --upgrade to upgrade): beautifulsoup4 
in /usr/local/lib/python2.7/dist-packages (from google)
Installing collected packages: google
  Running setup.py install for google
    changing mode of build/scripts-2.7/google.py from 644 to 755
    
    changing mode of /usr/local/bin/google.py to 755
Successfully installed google
Cleaning up...

As you can see the next step is to upgrade: beautifulsoup4 ...

# pip install --upgrade beautifulsoup4
Downloading/unpacking beautifulsoup4 from https://pypi.python.org/packages/
source/b/beautifulsoup4/beautifulsoup4-4.3.2.tar.gz#md5=
b8d157a204d56512a4cc196e53e7d8ee
  Downloading beautifulsoup4-4.3.2.tar.gz (143Kb): 143Kb downloaded
  Running setup.py egg_info for package beautifulsoup4
    
Installing collected packages: beautifulsoup4
  Found existing installation: beautifulsoup4 4.3.1
    Uninstalling beautifulsoup4:
      Successfully uninstalled beautifulsoup4
  Running setup.py install for beautifulsoup4
    
Successfully installed beautifulsoup4
Cleaning up...

Let's make a simple script to find linux word using google.com ...

>>> from google import search
>>> for url in search('linux', tld='com', lang='en', stop=2):
...     print(url)
... 
http://en.wikipedia.org/wiki/Linux
http://en.wikipedia.org/wiki/Unix-like
http://en.wikipedia.org/wiki/Linus_Torvalds
http://en.wikipedia.org/wiki/Linux_kernel
http://en.wikipedia.org/wiki/List_of_Linux_distributions
...

If you want to know more about google search function then use this:

>>> help(google.search)
Help on function search in module google:

search(query, tld='com', lang='en', num=10, start=0, stop=None, pause=2.0)
    Search the given query string using Google.
...    

... and this is all.

Saturday, November 30, 2013

How I saw the Comet C/2012 S1 ISON with python .

I use sunpy python module to see the Comet C/2012 S1 ISON and SOHO LASCO C3 instrument.
This is the result:

The script is simple.
$ python
Python 2.7.3 (default, Jan  2 2013, 16:53:07) 
[GCC 4.7.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import sunpy
>>> from sunpy.net.helioviewer import HelioviewerClient
>>> 
>>> hv = HelioviewerClient()
>>> datasources = hv.get_data_sources()
>>> 
>>> # print a list of datasources and their associated ids
... for observatory, instruments in datasources.items():
...     for inst, detectors in instruments.items():
...         for det, measurements in detectors.items():
...             for meas, params in measurements.items():
...                 print("%s %s: %d" % (observatory, params['nickname'], params['sourceId']))
... 
Yohkoh SXT AlMgMn: 33
Yohkoh SXT thin-Al: 34
Yohkoh SXT white-light: 35
PROBA2 SWAP 174: 32
STEREO_A EUVI-A 195: 21
STEREO_A EUVI-A 304: 23
STEREO_A EUVI-A 284: 22
STEREO_A EUVI-A 171: 20
STEREO_A COR2-A: 29
STEREO_A COR1-A: 28
STEREO_B EUVI-B 195: 25
STEREO_B EUVI-B 304: 27
STEREO_B EUVI-B 284: 26
STEREO_B EUVI-B 171: 24
STEREO_B COR2-B: 31
STEREO_B COR1-B: 30
SOHO MDI Mag: 6
SOHO MDI Int: 7
SOHO EIT 195: 1
SOHO EIT 304: 3
SOHO EIT 284: 2
SOHO EIT 171: 0
SOHO LASCO C3: 5
SOHO LASCO C2: 4
SDO AIA 1700: 16
SDO AIA 211: 12
SDO AIA 335: 14
SDO AIA 1600: 15
SDO AIA 304: 13
SDO AIA 193: 11
SDO AIA 131: 9
SDO AIA 4500: 17
SDO AIA 94: 8
SDO AIA 171: 10
SDO HMI Mag: 19
SDO HMI Int: 18
This show me all instruments from sunpy. You see all instruments online here
The next step is to take one png image :
>>> hv.download_png('2013/11/29 00:15:00', 50, "[SOHO,LASCO,C3,white-light,1,100]", x0=0, y0=0, width=768, height=768)
The settings are : date and time , the image resolution (arcseconds per pixel), the SOHO LASCO C3 instrument with the layer visibility , center points and size

Friday, November 8, 2013

Using python with Image, ImageFilter, ImageChops and custom image filter.

Today I will sow you some filters using python Image, ImageFilter and ImageChops.

I make this default python script to open one image and after will be delete from memory.See the default image:


I make also one python class named TEST_FILTER.

This class will have all data from filter, see filterargs.

The filterargs args it's one matrix and this will be the filter.

The default script ...

import Image
import ImageFilter
import ImageChops

class TEST_FILTER(ImageFilter.BuiltinFilter):
    name="TestFilter"
    filterargs = (3,3),10,0,(1,0,1,0,0,0,1,0,1)

def main ():
    filename = "test-gentoo.jpg"
    image = Image.open(filename);
    del image;
if (__name__ =="__main__"):
   main();

Let's try first filter : TEST_FILTER

import Image
import ImageFilter
import ImageChops

class TEST_FILTER(ImageFilter.BuiltinFilter):
    name="TestFilter"
    filterargs = (3,3),10,0,(1,0,1,0,0,0,1,0,1)

def main ():
    filename = "test-gentoo.jpg"
    image = Image.open(filename);
    image.filter(TEST_FILTER).show();
    del image;
if (__name__ =="__main__"):
   main();

The result will be this:


Now for each filter will change this source code...

    image.filter(TEST_FILTER).show();

...with the new filter source code.

Let's see some filters ...

EMBOSS - filter

    image.filter(ImageFilter.EMBOSS).show();

FIND_EDGES - filter

    image.filter(ImageFilter.FIND_EDGES).show();

BLUR - filter

    image.filter(ImageFilter.BLUR).show();

CONTOUR - filter

    image.filter(ImageFilter.CONTOUR).show();

DETAIL - filter

    image.filter(ImageFilter.DETAIL).show();

EDGE_ENHANCE - filter

    image.filter(ImageFilter.EDGE_ENHANCE).show();

Now image convert with bit 1.

    image.convert("1").show();

Invert image with ImageChops.

    ImageChops.invert(image).show();

Thursday, October 31, 2013

News Python 2.6.9 final was released on October 29 2013.

News about python from www.python.org.
Python 2.6.9 is a security-fix source-only release for Python 2.6.8, fixing several reported security issues: issue 16037, issue 16038, issue 16039, issue 16040, issue 16041, and issue 16042 (CVE-2013-1752, long lines consuming too much memory), as well as issue 14984 (security enforcement on $HOME/.netrc files), issue 16248 (code execution vulnerability in tkinter), and issue 18709 (CVE-2013-4238, SSL module handling of NULL bytes inside subjectAltName).

Monday, October 21, 2013

Python versus Matlab - good article by Luis Pedro Coelho

Luis Pedro Coelho is a computational biologist at EMBL.
In this article Luis Pedro Coelho come with many arguments about Python versus Matlab.
Very good article ...

Thursday, October 17, 2013

How to make a color gradient and images with python script.

The Image and ImageDraw provide simple 2D graphics to create new images, annotate or retouch existing images, and to generate graphics.

Also this can help you to make on the fly images for you.

Let's see one example ...

First you need to import this modules and random python module

import Image,ImageDraw
from random import randint as rint

The next step : make one image , get some random numbers...

You need two colors : first is one random color and second is make from first color, see next source code:

img = Image.new("RGB", (500,500), "#FFFFFF")
draw = ImageDraw.Draw(img)
r,g,b = rint(0,255), rint(0,255), rint(0,255)
dr = (rint(0,255) - r)/500.
dg = (rint(0,255) - g)/500.
db = (rint(0,255) - b)/500.

Now you need to draw lines with this gradient of two colors.

    for i in range(500):
        r,g,b = r+dr, g+dg, b+db
        draw.line((i,0,i,500), fill=(int(r),int(g),int(b)))

... and the python script source code:

import Image,ImageDraw
from random import randint as rint

def random_gradient(name):
    img = Image.new("RGB", (500,500), "#FFFFFF")
    draw = ImageDraw.Draw(img)

    r,g,b = rint(0,255), rint(0,255), rint(0,255)
    dr = (rint(0,255) - r)/500.
    dg = (rint(0,255) - g)/500.
    db = (rint(0,255) - b)/500.
    for i in range(500):
        r,g,b = r+dr, g+dg, b+db
        draw.line((i,0,i,500), fill=(int(r),int(g),int(b)))

    img.save(name+".png", "PNG")

if __name__ == "__main__":
    for name in range(10):
        random_gradient(str(name))

The result of this script will make images :

Sunday, September 22, 2013

Jython - funny and simple scripts - first steps .

I play today with jython and can be fun but seams to be to slow in a linux os.

Jython is invoked using the "jython" script and it's an implementation of Python for the JVM.

Install the package jython in your linux distro and you can start to deal with java and python.

When you use jython then script will start with :

#!/usr/bin/env jython

I make also some very simple scripts...

First script make one button and give a action to exit.


#!/usr/bin/env jython
from javax import *
import java
from java import *
import sys

frame = awt.Frame(size=(500,100))
frame.background = 255,255,0
def exit(event):
  java.lang.System.exit(0)

my_button = awt.Button("Exit!", actionPerformed=exit)
frame.add(my_button,"Center")
frame.pack()
frame.setVisible(1)

The output is:


The script is easy to make ... it's like gtk with add, pack and action ...

Let's see the next script : one list.

from javax import *
from java import awt
import sys
python_list=[]
python_list.append('text 1')
python_list.append('text 2')
python_list.append('text 3')
python_list.append('text 4')
python_list.append('text 5')

frame=awt.Frame("test list")
panel=swing.JList(python_list)
frame.add(panel,"Center")
frame.pack()
frame.setVisible(1)

... and this is the gui with the list:


I make a simple list and add to the gui using pack() function.

The jython is not easy is much to learn and if you want then go to this website.

Check system , distro and commands using python scripts .

This is a simple example with two functions.

First will check the linux command : ls linux command.

The next function will give us some infos about system.

import shlex 
import subprocess
from subprocess import Popen, PIPE

import platform

def check_command(command):
    cmd='which ' + command 
    output = Popen(shlex.split(cmd), stdout=PIPE).communicate()[0]
    command_path =output.split('\n')[0]
    print command_path
    return command_path

def check_platform():
    arch, exe = platform.architecture()
    my_system = platform.system()
    if my_system == 'Linux':
        distro_name, distro_version, distro_id = platform.linux_distribution()
    elif my_system == 'Darwin':
        distro_name, distro_version, distro_id = platform.mac_ver()
    elif my_system == 'Windows':
 distro_name, distro_version, distro_id = platform.win32_ver()
    elif my_system == 'Java':
 distro_name, distro_version, distro_id = platform.java_ver()
    processor = platform.processor() or 'i386'
    print processor, my_system, arch, distro_name, distro_version, distro_id
    return processor, my_system, arch, distro_name, distro_version, distro_id

check_command('ls')

check_platform()

This python script can be use with any scripts when we need to test commands and system , distro version.

Thursday, September 12, 2013

Working with SunPy python module - part 001 .

The SunPy python module it's an open-source software library for solar physics using the Python programming language.

The SunPy module is included into nasa projects.

Now, if you want to use this python module then you need to install lapack and blas libraries for development.

I use # pip under super user account to install sunpy and the python modules required by SunPy.

# pip install --upgrade distribute
# pip install --upgrade pyfits
# pip install --upgrade suds
# pip install --upgrade pandas
# pip install --upgrade beautifulsoup4

... also you need to have this python modules: Scipy and Matplotlib.

After that you can install sunpy using:

# pip install sunpy
# pip install --upgrade sunpy

The basic example is one output created by Map() function.

This function can deal with many data sources, like:

SDO/AIA, SDO/HMI

STEREO/EUVI, STEREO/COR

Hinode/XRT

SOHO/EIT, SOHO/LASCO, SOHO/MDI

PROBA2/SWAP

Yohkoh/SXT

Let's try a simple example and will show the result...

>>> import sunpy 
>>> ati_map=sunpy.Map(sunpy.AIA_171_IMAGE).peek()

... and output is:


Let's make more sun maps...

>>> eit_map=sunpy.Map(sunpy.EIT_195_IMAGE).peek()

The the output is:


>>> rhessi_map=sunpy.Map(sunpy.RHESSI_IMAGE).peek()

You can see radio spectrometer image using:

>>> callisto_radio_maps=sunpy.Map(sunpy.CALLISTO_IMAGE).peek()

Also you can combine the maps , like in the next example:

>>> eti_rhessi_maps=sunpy.Map(sunpy.EIT_195_IMAGE, sunpy.RHESSI_IMAGE, composite=True).peek()

You can get more infos about Map using :

>>> help(sunpy.Map)

If you want more data to show then you can request data from here.

Also you can give parameters to the Map, like:

date : datetime
 |          Image observation time
...

This allow you to take more data and info...

Using matplotlib and scipy modules can help to parse and show all infos.

How to fix error: fatal error: Python.h: No such file or directory

This is a common error when your system don't have the python-dev.

I got this error when I try to use : pip .

Just install the package python-dev and then all will working well.

Monday, September 9, 2013

News - Python 3.4.0 Alpha 2 was released .

From python official website I found this :

Python 3.4.0 alpha 2 was released on September 9th, 2013. This is a preview release of the next major release of Python, Python 3.4, and is not suitable for production environments.

Major new features of the 3.4 series, compared to 3.3

Python 3.4 includes a range of improvements of the 3.x series, including hundreds of small improvements and bug fixes. Major new features and changes in the 3.4 release series so far include:

PEP 435, a standardized "enum" module

PEP 442, improved semantics for object finalization

PEP 443, adding single-dispatch generic functions to the standard library

PEP 445, a new C API for implementing custom memory allocators

PEP 446, changing file descriptors to not be inherited by default in subprocesses...

Saturday, August 17, 2013

Working with PEP 8 conventions ...

I am wrote my own python scripts to long time ago and now I saw many of this scripts are a mess  in terms of PEP criteria.
What is the pep criteria? The PEP describing style guidelines for the C code in the C implementation of Python.
If you using Blender 3D/Python development  then you need to follow the PEP 8.
The PEP 8 and can be found here and the authors are: Guido van Rossum , Barry Warsaw and Nick Coghlan.
Today I will show you a brief listing of pep8 criteria:
-indentation of 4 spaces not use tabs
-camel caps for class names: MyClass , AnotherClass
-all lower case underscore separated module names: my_module, another_module
-use explicit imports, not importing '*'
-imports should usually be on separate lines, not import os,sys
-adding whitespace around the operators , not 1+2 or 7+ 3
-don't use spaces around the = sign , not a = b +1
-use single quotes for enums, and double quotes for strings
-each line of a block comment starts with a # and a single space
-don't make comments that contradict the code
-if you want to writing good documentation strings then follow the PEP 257 conventions.
-run checks for pep8 compliance
# <pep8 compliant=""></pep8>
-and enable line length checks use this instead
# <pep8-80 compliant=""></pep8-80>
-don't use multiple statements on the same line, like:
if foo == 'test': do_test_thing()
one_test(); two_test()
... this is the correct way:
if foo == 'test':
    do_test_thing()
one_test()
two_test()
Also you can read about Blender 3D/Python and PEP 8 best practice here.

Saturday, August 10, 2013

Fix python error: SyntaxError: Non-ASCII character.

This can be fix easy ... just add the below line at top of the python file:
# coding: utf-8
You will see now something like this error:
SyntaxError: invalid syntax
... but also will be point to the bad encoding character with : ^
For example I had this:
usertest@home:~$ python sunet.py 
  File "sunet.py", line 22
    def  __init__ ( self , a , b , c ) :
                                 ^
SyntaxError: invalid syntax

How to deal with environment variables using python script.

Any OS like Linux, Unix, Windows has environment variables.

Also any variables which must not be committed on a public code can be used in this way.

You can give this variables to your application.

Let's see one simple example about how to do that:

import os
ENV_VAR = os.environ.get("ENV_VAR", None)
if not ENV_VAR:
        print "not ENV_VAR"
if ENV_VAR:
        print "yes ! is ENV_VAR"

Now you can give this ENV_VAR to the script or not. See next...

usertest@home:~$ ENV_VAR=true python demo-env.py 
yes ! is ENV_VAR
usertest@home:~$ python demo-env.py 
not ENV_VAR

With Python 3 on Unix, environment variables are decoded using the file system encoding.

Tuesday, July 30, 2013

The new pygobject come with version 3.9.5 .

GObject is a object system used by GTK+, GStreamer and other libraries.

The new PyGObject 3.9.5 provides a convenient wrapper for use in Python programs when
accessing GObject libraries.

The news come from Simon Feltman - pygtk digest: I am pleased to announce version 3.9.5 of the Python bindings for
GObject. This is the third release of the 3.9.x series which will
eventually result in the stable 3.10 release for GNOME 3.10.

The new release is available from ftp.gnome.org.

Wednesday, July 24, 2013

Using python module webkit and gtk to make one simple webbrowser.

Today I will show you a simple example with webkit python module.

I will make one simple browser using this two python modules.

Read the full tutorial here.

The result can be see in the next image:

Sunday, July 14, 2013

Selenium python module and links.

Just see my old tutorial to run the selenium module.
NOTE: If your script not run when you try to login then use python shell :P
Now add the next source code to see the links and some infos.
links = browser.find_elements_by_partial_link_text('')
for link in links:
    print link.get_attribute("href")

Saturday, July 13, 2013

Selenium python module and cookies.

Today I will show how to deal with cookies and Firefox.

Selenium Python Client Driver is a Python language binding for Selenium Remote Control.

You can read more about this module here.

You can find some examples , but most of webpages working with cookies.So let's make one simple tutorial.

The next source code is very simple and most of the python users knows what means.


$ python 
Python 2.7.3 (default, Jan  2 2013, 16:53:07) 
[GCC 4.7.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from selenium import webdriver
>>> from selenium.common.exceptions import NoSuchElementException
>>> from selenium.webdriver.common.keys import Keys
>>> browser = webdriver.Firefox()
>>> browser.get("http://facebook.com/")
>>> browser.get("http://facebook.com/home.php")

The next source codes will get your cookies from the webpage.

>>> for cookie in browser.get_cookies():
...     print(cookie['name'] + ' --> your cookie data ' + cookie['value'])
... 
datr --> your cookie data 
locale --> your cookie data 
xs --> your cookie data 
s --> your cookie data 
lu --> your cookie data 
fr --> your cookie data 
csm --> your cookie data 
c_user --> your cookie data 
act --> your cookie data 
x-src --> your cookie data 
sub --> your cookie data 
p --> your cookie data 
presence --> your cookie data 
>>> 

You can deal with all functions of selenium python module , see :

>>> dir(browser)
['NATIVE_EVENTS_ALLOWED', '__class__', '__delattr__', '__dict__', '__doc__', 
'__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__'
, '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__'
, '__subclasshook__', '__weakref__', '_is_remote', '_unwrap_value', '_wrap_value'
, 'add_cookie', 'application_cache', 'back', 'binary', 'capabilities', 'close', 
'command_executor', 'create_web_element', 'current_url', 'current_window_handle'
, 'delete_all_cookies', 'delete_cookie', 'desired_capabilities', 'error_handler'
, 'execute', 'execute_async_script', 'execute_script', 'find_element', 
'find_element_by_class_name', 'find_element_by_css_selector', 'find_element_by_id'
, 'find_element_by_link_text', 'find_element_by_name', 'find_element_by_partial_link_text'
, 'find_element_by_tag_name', 'find_element_by_xpath', 'find_elements', 
'find_elements_by_class_name', 'find_elements_by_css_selector', 'find_elements_by_id',
 'find_elements_by_link_text', 'find_elements_by_name', 'find_elements_by_partial_link_text'
 , 'find_elements_by_tag_name', 'find_elements_by_xpath', 'firefox_profile', 'forward',
  'get', 'get_cookie', 'get_cookies', 'get_screenshot_as_base64', 'get_screenshot_as_file'
  , 'get_window_position', 'get_window_size', 'implicitly_wait', 'is_online', 
  'maximize_window', 'name', 'orientation', 'page_source', 'profile', 'quit', 'refresh'
  , 'save_screenshot', 'session_id', 'set_page_load_timeout', 'set_script_timeout', 
  'set_window_position', 'set_window_size', 'start_client', 'start_session', 'stop_client'
  , 'switch_to_active_element', 'switch_to_alert', 'switch_to_default_content', 
  'switch_to_frame', 'switch_to_window', 'title', 'window_handles']

This module can be a way for you to testing your webpages , save cookie , restore and more...

Also , if you know networking development also you can use scapy module to test more.

I hope will like this simple tutorial about python.

Monday, July 8, 2013

Using findContours from OpenCV python module.

Today I will show something nice about OpenCV Analysis and Shape Descriptors.

This function finds contours in a binary image.

All detected contours is stored as a vector of points for each contour.


#!/usr/bin/python2.7
import cv2
im = cv2.imread('your_image.jpg')
img_gray = cv2.cvtColor(im,cv2.COLOR_RGB2GRAY)
ret,thresh = cv2.threshold(img_gray,127,255,0)
contours, hierarchy = cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
cv2.drawContours(im,contours,-1,(250,250,250),2)
cv2.imshow('your_image.jpg',im)
cv2.waitKey()
cv2.destroyAllWindows()

If you got this error:

findContours error 'support only 8uC1 images'

then the main reason it's findContours requires a monochrome image.

Let's see the result of the python script.


The contour it's draw with 250,250,250 color.

Friday, June 21, 2013

Simple way to find your script under linux.

Many python users have a lot of scripts.

They use some words for classes or some functions.

Sometime is hard to remember where it's this scripts.

So the easy way to do that is to find the script where is some words.

For example you need to find this : word_in_your_script

To do that just see next linux command:

$ find ~/ -type f -iname "*.py" -exec grep -l 'word_in_your_script' {} \;

Thursday, June 13, 2013

What you need : stdout or print ?

My question is much more complicated than intended and I will show you in this tutorial.

Most users use print or print() - if it used in python 3.

For example you can use this without import any python module.

$ python 
Python 2.6.8 (unknown, Apr 14 2013, 18:10:41) 
[GCC 4.3.2 20081105 (Red Hat 4.3.2-7)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> print "my text"
my text
>>> 

This is simple to show some strings.

What the most people don't know about print function it's the interface of stdout.write.

Let's see another example with stdout.write .

>>> sys.stdout.write(str(my text) + '\n')   
  File "<stdin>", line 1
    sys.stdout.write(str(my text) + '\n')
                               ^
SyntaxError: invalid syntax
>>> sys.stdout.write(str("my text") + '\n')                  
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'sys' is not defined

First error tells us about function str.It's need just one arg not this my text.

The next error tells us about sys module is not import by python.

Note: This restriction can help us sometime.

Some example using stdout.write :

First is : my text example , see I add '\n' to go to the next row.

>>> import sys 
>>> sys.stdout.write("my text"+'\n')
my text

Let's try to change the output.

See the next image :

You can say : I can do this with print function.

>>> print "\033[0;32m"+"my text"+"\033[0m"
my text

Yes! Right. Can you do this ? (see the next video)


Wednesday, May 15, 2013

Use python to render scene in Blender 3D.

The python script is very simple.

I used my scene with Mickey Mouse (my boy like this funny cartoon).

This is the python script.

import bpy
bpy.context.scene.render.use_border = False
bpy.context.scene.render.use_crop_to_border = False
bpy.ops.render.render()
R="Render Result"
bpy.data.images[R].save_render("/home/your_username/test_render.png")

See the output image:


The next source code it's used for border and crop.

Only if you want to use it.

bpy.context.scene.render.use_border = False
bpy.context.scene.render.use_crop_to_border = False

Also you can use this to set resolution percentage.

For example if you want to render just 10% of resolution use this:

bpy.context.scene.render.resolution_percentage =10

Saturday, March 23, 2013

Using fnmatch python module ...

The module fnmatch provides support for Unix shell-style wildcards, which are not the same as regular expressions.

Why , because the special characters used are : * , ? , [seq] , [!seq] .

This is default example from fnmach website.


>>> for file in os.listdir('.'):
...  if fnmatch.fnmatch(file, '*.txt'):
...   print file
... 
tableta.txt
verf.txt
a.txt
python-modules.txt
untitled.txt
resetbios.txt
>>> 

Now I want to show you another way to use this module.

Using Blender with multiple objects and python script can be very hard way.

For example if you have many objects or one matrix of objects create manually or with some scripts the named object is like in the next image:


Just use the fnmatch to sort this objects.

>>> import bpy 
>>> import fnmatch

Now get all meshes objects.

>>> all_objects = bpy.data.objects

Put names of all meshes as a list of strings.

>>> list_all_objects= [all_objects[i].name for i in range(len(all_objects))]

Use the python module fnmatch to filter the name of objects.

>>> new_list_objects = fnmatch.filter(list_all_objects, 'Cube.*')]

Now you can use this new list to make some change. I use print to show test the list.

>>> print(new_list_objects)
['Cube.001', 'Cube.002', 'Cube.003'

The goal of fnmatch module in Blender 3D can be use one module to make list of objects and enables searching for files given a file name pattern.

It's two features in one module.

Also this python module can be used to get some

>>> regular_expression_txt = fnmatch.translate('*.txt')
>>> regular_expression_txt
'.*\\.txt\\Z(?ms)'
>>> print(regular_expression_txt)
.*\.txt\Z(?ms)

Just remove \Z(?ms) and use it.

I try to use some regular expression and seam working well.

Saturday, March 2, 2013

Simple way to reverse strings

Just see the next source code:

>>> text='0123456789'
>>> reverse_text=text[::-1]
>>> print reverse_text
9876543210
>>> 

Monday, February 25, 2013

Make Newton fractal with python

A fractal is a mathematical set that has a fractal dimension that usually exceeds its topological dimension , see Fractal wikipedia.

Today I used my mind and also my python skills to make one fractal image.

I use Newton's method to make all points and PIL python module to save the result.

Let's see the source code and comments.

from PIL import Image
#size of image
imgx = 600
imgy = 400
#make image buffer
image = Image.new("RGB", (imgx, imgy))

# area of fractal
xa = -2.0
xb = 2.0
ya = -2.0
yb = 2.0

#define constants
max_iterations = 10 # max iterations allowed
step_derivat = 0.002e-1 # step size for numerical derivative
error = 5e-19 # max error allowed

# function will generate the newton fractal
def f(z): return z * z  + complex(-0.31,0.031)

# draw derivate fractal for each y and x 
for y in range(imgy):
 zy = y * (yb - ya)/(imgy - 1) + ya
 for x in range(imgx):
  zx = x * (xb - xa)/(imgx - 1) + xa
  z = complex(zx, zy)
  for i in range(max_iterations):
   # make complex numerical derivative
   dz = (f(z + complex(step_derivat, step_derivat)) - f(z))/complex(step_derivat,step_derivat)
 # Newton iteration see wikipedia   
   z0 = z - f(z)/dz 
   # stop to the error 
   if abs(z0 - z) < error: 
    break
   z = z0
  #I use modulo operation expression to do RGB colors of the pixels 
  image.putpixel((x, y), (i % 8 * 16, i % 4 * 32,i % 2 * 64))
  
#save the result 
image.save("fractal.png", "PNG")

This is the final result of Newton fractal image:

Sunday, February 24, 2013

PP 1.6.4 is released ...

The new version : PP 1.6.4 is released and working well.

What is PP python module?

PP is a python module which provides mechanism for parallel execution of python code on SMP and clusters.

SMP - systems with multiple processors or cores;

clusters - computers connected via network;

Read more Parallel Python.

Saturday, January 26, 2013

Using Flask to build websites in Python.

The python module Flask is a small web framework.

Install the module using pip.

(my_new_env)[free-tutorials@free-tutorials ~]$ pip install Flask
Downloading/unpacking Flask
  Downloading Flask-0.9.tar.gz (481kB): 481kB downloaded
  Running setup.py egg_info for package Flask
    
    warning: no files found matching '*' under directory 'tests'
    ...
    ...
Successfully installed Flask Werkzeug Jinja2
Cleaning up...

Create the next python script and save as : flask-web.py .

from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello World!'

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

Run the python script:

(my_new_env)[free-tutorials@free-tutorials ~]$ python flask-web.py 
 * Running on http://127.0.0.1:5000/
127.0.0.1 - - [25/Jan/2013 00:10:35] "GET / HTTP/1.1" 200 -
127.0.0.1 - - [25/Jan/2013 00:10:36] "GET /favicon.ico HTTP/1.1" 404 -
127.0.0.1 - - [25/Jan/2013 00:10:36] "GET /robots.txt HTTP/1.1" 404 -
127.0.0.1 - - [25/Jan/2013 00:10:36] "GET /favicon.ico HTTP/1.1" 404 -
127.0.0.1 - - [25/Jan/2013 00:10:36] "GET /robots.txt HTTP/1.1" 404 -

You will see something like this:

Also you can try the quickstart tutorial here.

The sandboxed Python - development environments using pip and virtualenv .

Use pip and virtualenv and you can make sandboxed Python development environments.

With this tools such as pip and virtualenv you have total control over the development environment.

Why? Because if your project is developed by a team with mutiple developers then they prefer having exactly replicated environments.

Let's try some simple example commands:

1. Start your environment ( in my case is: my_new_env ).

[free-tutorials@free-tutorials ~]$ python virtualenv.py my_new_env
New python executable in my_new_env/bin/python
Installing setuptools..................done.
Installing pip.............done.

Activate your environment ( in my case is: my_new_env ).

[free-tutorials@free-tutorials ~]$ . my_new_env/bin/activate

Let's see the pip --help command :

(my_new_env)[free-tutorials@free-tutorials ~]$ pip --help
Usage: pip COMMAND [OPTIONS]
 --version                    show program's version number and exit
 -h, --help                   Show help
 -v, --verbose                Give more output
 -q, --quiet                  Give less output
 --log <filename>             Log file where a complete (maximum verbosity)
                              record will be kept
 --proxy <proxy>              Specify a proxy in the form
                              user:passwd@proxy.server:port. Note that the
                              user:password@ is optional and required only if
                              you are behind an authenticated proxy. If you
                              provide user@proxy.server:port then you will be
                              prompted for a password.
 --timeout <seconds>          Set the socket timeout (default 15 seconds)
 --exists-action <exists_action>
                              Default action when a path already exists. Use
                              this option more than one time to specify
                              another action if a certain option is not
                              available. Choices: (s)witch, (i)gnore, (w)ipe,
                              (b)ackup

Commands available:
  bundle: Create pybundles (archives containing multiple packages)
  freeze: Output all currently installed packages (exact versions) to stdout
  help: Show available commands
  install: Install packages
  search: Search PyPI
  uninstall: Uninstall packages
  unzip: Unzip individual packages
  zip: Zip individual packages

Now we will use freeze and install.

I will list all the pip packages used in my virtual environment.

(my_new_env)[free-tutorials@free-tutorials ~]$  pip freeze -l
PyOpenGL==3.0.2
PyOpenGL-accelerate==3.0.2

Put all the output in my_packages.txt file.

(my_new_env)[free-tutorials@free-tutorials ~]$ pip freeze -l > my_packages.txt

Install my packages from my_packages.txt .

(my_new_env)[free-tutorials@free-tutorials ~]$ pip install -r my_packages.txt
Requirement already satisfied (use --upgrade to upgrade): PyOpenGL==3.0.2 in 
./my_new_env/lib/python2.7/site-packages (from -r my_packages.txt (line 1))
Requirement already satisfied (use --upgrade to upgrade): PyOpenGL-accelerate==3.0.2 in 
./my_new_env/lib/python2.7/site-packages (from -r my_packages.txt (line 2))
Cleaning up...

Let's try now to find one python module : opencv .

(my_new_env)[free-tutorials@free-tutorials ~]$ pip search opencv 
remotecv                  - remotecv is an OpenCV server for facial and
                            feature recognition
ctypes-opencv             - ctypes-opencv - A Python wrapper for OpenCV using
                            ctypes
pyopencv                  - PyOpenCV - A Python wrapper for OpenCV 2.x using
                            Boost.Python and NumPy
opencv-cython             - An alternative OpenCV wrapper
CVtypes                   - Python OpenCV wrapper using ctypes
Tippy                     - another Toolbox for Image Processing in PYthon,
                            based on OpenCV

You can see where the version of python you are using installs to by running it the next python code.

>>> import sys
>>> sys.prefix
'/home/free-tutorials/my_new_env'
>>> sys.exec_prefix
'/home/free-tutorials/my_new_env'

To leave your environment just type next command: $ deactivate.

I will come with new tutorials about pip and virtualenv .

See you later.