python-catalin

Thursday, March 9, 2023

Python 3.11.0 : The yattag python package.

Yattag is a Python library for generating HTML or XML in a pythonic way.

You can find more information on the official webpage.

Installation can be done easily with the pip utility:

pip install yattag --user

I test a simple example code from the official documentation and works well:

from yattag import Doc

doc, tag, text = Doc(
    defaults = {
        'title': 'Untitled',
        'contact_message': 'You just won the lottery!'
    },
    errors = {
        'contact_message': 'Your message looks like spam.'
    }
).tagtext()

with tag('h1'):
    text('Contact form')
with tag('form', action = ""):
    doc.input(name = 'title', type = 'text')
    with doc.textarea(name = 'contact_message'):
        pass
    doc.stag('input', type = 'submit', value = 'Send my message')

print(doc.getvalue())

Sunday, March 5, 2023

Python Qt5 : OpenStreetMap with PyQtWebEngine.

You need to install the PyQtWebEngine python package and to have the PyQt5 python package installed.

PyQt6 works in the same way as PyQt5 but with small differences ...

pip install PyQtWebEngine --user
Collecting PyQtWebEngine
  Downloading PyQtWebEngine-5.15.6-cp37-abi3-win_amd64.whl (182 kB)
     ---------------------------------------- 182.7/182.7 kB 580.6 kB/s eta 0:00:00
...
     ---------------------------------------- 60.0/60.0 MB 655.7 kB/s eta 0:00:00
...
Installing collected packages: PyQtWebEngine-Qt5, PyQtWebEngine
Successfully installed PyQtWebEngine-5.15.6 PyQtWebEngine-Qt5-5.15.2

import sys
from PyQt5.QtWebEngineWidgets import QWebEngineView
from PyQt5.QtWidgets import QApplication, QWidget, QVBoxLayout

class MapWidget(QWidget):
    def __init__(self, parent=None):
        super().__init__(parent)

        # Create a QWebEngineView object to display the map
        self.map = QWebEngineView()
        self.map.setHtml("""
            <!DOCTYPE html>
            <html>
                <head>
                    <meta name="viewport" content="width=device-width, initial-scale=1.0">
                    <style>
                        #map {
                            height: 100%;
                        }
                    </style>
                </head>
                <body>
                    <div id="map"></div>
                    <script src="https://openlayers.org/en/v4.6.5/build/ol.js"></script>
                    <script>
                        var map = new ol.Map({
                            target: 'map',
                            layers: [
                                new ol.layer.Tile({
                                    source: new ol.source.OSM()
                                })
                            ],
                            view: new ol.View({
                                center: ol.proj.fromLonLat([0, 0]),
                                zoom: 2
                            })
                        });
                    </script>
                </body>
            </html>
        """)

        # Create a QVBoxLayout to hold the map widget
        layout = QVBoxLayout()
        layout.addWidget(self.map)
        self.setLayout(layout)

if __name__ == '__main__':
    app = QApplication(sys.argv)
    widget = MapWidget()
    widget.show()
    sys.exit(app.exec_())

The run of this python script will show a window with the OpenStreetMap map.

Friday, March 3, 2023

Python 3.11.0 : OpenCV - part 001.

A few years ago I made a series of several tutorials about python and OpenCV. They were functional, but I know that due to time, changes in development can lead to changes in the source code. Today I tested a script with this python package and it worked quite well.

In some cases, depending on the web camera and the operating system, the way of capturing images can be modified with the two specific elements: cv2.VideoCapture(cv2.CAP_DSHOW) or cv2.VideoCapture(cv2.CAP_V4L2)

This is the source code I used:

import cv2
import numpy as np
import time 

def draw_hist(name, gray):
    hist = cv2.calcHist([gray], [0], None, [256], [0,256])
    MAX = max(hist)
    plot = np.zeros((512,1024))
    for i in range(255):
        x1 = 4*i
        x2 = 4*(i+1)
        y1 = int(hist[i]*512/MAX)
        y2 = int(hist[i+1]*512/MAX)
        cv2.line(plot, (x1,y1), (x2,y2), 1, 3)
    cv2.imshow(name + "-gray", gray)
    cv2.imshow(name + "-hist", plot)


def main():
    cam = cv2.VideoCapture(0)
    #while cv2.waitKey(10) == -1:
    start_time = time.time()
    while time.time() - start_time < 30:
        ret, img = cam.read()
        if not ret:  # add check for empty image
            continue
        gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
        draw_hist("cam",gray)
        cv2.waitKey(10)

if __name__=="__main__":
    main()

This is the result:

Wednesday, March 1, 2023

Python 3.11.0 : The sunpy python package - part 002.

In the last article tutorial, I show some simple examples with the sunpy python package.

Today I installed it again with all of these python packages using the pip tool.

You don't need all of these if you just start, but in time you will need to install them:

pip install sunpy --user
Collecting sunpy
  Downloading sunpy-4.1.3.tar.gz (3.6 MB)
     ---------------------------------------- 3.6/3.6 MB 3.6 MB/s eta 0:00:00
     ...
     Successfully installed PyYAML-6.0 aioftp-0.21.4 astropy-5.2.1 pyerfa-2.0.0.1 sunpy-4.1.3
...
pip install zeep --user
Collecting zeep
  Using cached zeep-4.2.1-py3-none-any.whl (101 kB)  
  ...
  Successfully installed isodate-0.6.1 pytz-2022.7.1 requests-file-1.5.1 requests-toolbelt-0.10.1 zeep-4.2.1
  ...
pip install drms --user
Collecting drms
  Downloading drms-0.6.3-py3-none-any.whl (35 kB)
  ...
  Successfully installed drms-0.6.3 pandas-1.5.3
pip install hvpy --user
Collecting hvpy
  Downloading hvpy-1.0.1-py3-none-any.whl (44 kB)
     ---------------------------------------- 44.0/44.0 kB 359.5 kB/s eta 0:00:00
     ...
     Successfully installed hvpy-1.0.1
pip install scipy --user
Collecting scipy
  Downloading scipy-1.10.1-cp311-cp311-win_amd64.whl (42.2 MB)
     ---------------------------------------- 42.2/42.2 MB 7.4 MB/s eta 0:00:00
     ...
     Successfully installed scipy-1.10.1 
pip install glymur --user
Collecting glymur
  Downloading Glymur-0.12.2-py3-none-any.whl (2.7 MB)
     ---------------------------------------- 2.7/2.7 MB 4.2 MB/s eta 0:00:00
     ...
     Successfully installed glymur-0.12.2

Let's use the 1600 Angstrom from these all data of spectral range: 335 Angstrom, 131 Angstrom, 191-195 Angstrom, 211 Angstrom, 1600 Angstrom, 1700 Angstrom, 4500 Angstrom, 171-175 Angstrom, 304 Angstrom, 94 Angstrom

from datetime import datetime
from hvpy import createMovie, DataSource, create_events, create_layers
createMovie(
     startTime=datetime(2023, 2, 27),                    # start from 1st September 2022
     endTime=datetime(2023, 2, 28),                      # end at 5th September 2022
     layers=create_layers([(DataSource.AIA_1600, 100)]), # use AIA_193 Lens with 100% Opacity
     events=create_events(["CH"]),                      # show the Active regions
     eventsLabels=True,                                 # event labels should be included
     imageScale=1,                                      # Image scale in arcseconds per pixel
     hq=True,                                           # Download a higher-quality movie file
     timeout=10,                                        # Wait 10 minutes to get a response
     overwrite=True
)

The result is a video that looks like this :

There are easier ways to get information about the sun…

You can take one screenshot using the api.helioviewer.org feature in your browser.

https://api.helioviewer.org/v2/takeScreenshot/?imageScale=1&layers=[SDO,AIA,AIA,304,1,100]&events=&eventLabels=true&scale=true&scaleType=earth&scaleX=0&scaleY=0&date=2023-02-28T15:00:00.000Z&x1=-1100.0&x2=1100.0&y1=-1100.0&y2=1100.0&display=true&watermark=true&events=[CH,all,1]

You can find movies of the last two days of HMI magnetograms and intensitygrams on this webpage.

Monday, February 27, 2023

Python 3.11.0 : EbookLib python library - part 002.

The last version 3.3 of this file type was published by the EPUB 3 Working Group as a Candidate Recommendation Snapshot on 21 February 2023 ...

I haven't written about the ePub format and python since 2022 because I was busy with all kinds of tasks.

Then I presented a short introduction with some examples on how to create an ePUB file, see that tutorial article.

I like this file type, especially the last format that allows many features, including inserting SVG vector files.

Installing the package is easy on a windows 10 with the pip utility.

pip install ebooklib --user

In the folder with the svg image named cover.svg I created a python file with this content.

from ebooklib import epub

# Create a new EPUB book
book = epub.EpubBook()

# Set the book metadata
book.set_title('My EPUB Book')
book.set_language('en')

# Add a cover image
cover_svg = epub.EpubItem(uid="cover_svg", file_name="cover.svg", media_type="image/svg+xml", content=open("cover.svg").read())
book.add_item(cover_svg)

# Create a new chapter for the cover page
cover_page = epub.EpubHtml(title='Cover Page', file_name='cover.xhtml', lang='en')
cover_page.content = '<img alt="Cover Image" src="cover.svg" />'

# Add the cover page to the book
book.add_item(cover_page)

# Add a chapter to the book
chapter1 = epub.EpubHtml(title='Chapter 1', file_name='chap_1.xhtml', lang='en')
chapter1.content = '<h1>Chapter 1</h1><p>This is the first chapter of my book.</p>'

# Add the chapter to the book
book.add_item(chapter1)

# Create the spine
book.spine = [cover_page, chapter1]

# Generate the EPUB file
epub.write_epub('my_book.epub', book, {})

after running the script this was the result a epub file named my_book.epub.

The result is this simple epub with an SVG file from Wikipedia, see the screenshot take with the Sumatra PDF free software.

Saturday, February 25, 2023

Python 3.8.10 : My colab tutorials - part 031.

I update my source code for the collaboratory google tool. This colab notebook comes with source code for an update of IPython, PyTikTokAPI python module using the cookies browser, and a simple OpenCV test to create an image and show with google.colab.patches.

The cookies for the TikTok package module can be found in any browser by pressing the F12 key.

I don't find a good python package that parse the tiktok content.

The application for development with TikTok looks like Instagram and Facebook ... you can test it at https://developers.tiktok.com/app/.

Sunday, February 19, 2023

Python 3.8.10 : My colab tutorials - part 030.

You can see an exemple with the new changes on my GitHub colab project.

Tuesday, February 14, 2023

News : Colab changes ...

Python 2 is no longer supported in Colab and cells runs iron python.

All information you need on migrating your code from Python 2 to Python 3 can be found on Porting Python 2 Code to Python 3.

You can see these changes on the GitHub project.

Thursday, February 9, 2023

Python 3.6.9 : Anvil platform for web with python - part 001.

Anvil is a platform for building and hosting full-stack web apps written entirely in Python. Drag and drop your UI, then write Python on the front-end and back-end to make it all work ...

Yesterday I tested Anvil with python and was amazed at how simple it can be used to develop a web application. Anvil use python version 3.6.9. The tutorial I tested is available on the official website and is a feedback form that sends an email with your name, email address and content to your Anvil account address.

You can see this web application I follow from web tutorials on this webpage.

You can find some tutorials on this webpage.

How it works: Create a free account that can also be paid for via a web interface that you build with drag and drop and populate interface properties, add defined python modules and services, and write source code. I noticed that it uses beginner level python decorators and not very complex source code. The good part is that it is a fast development and the bad part is that it is limited to the free tier. After only three emails received, they came back with messages saying: ... his email quota has been exceeded.

These are features for anvil, I used in my project just the email:

Saturday, February 4, 2023

Python 3.7.0 : CodeSkulptor online compiler and editor.

CodeSkulptor uses Skulpt to provide a browser-based coding environment and can be tested on the official website.

You can see an online default example with simplegui python package on that website with online editor.

Saturday, January 28, 2023

Python : Fix error with pip and pylupdate6.exe .

I try to upgrade the PyQt6 package and I got this error:


pip3 install --upgrade --force-reinstall PyQt6
...
ERROR: Could not install packages due to an OSError: [WinError 2] The system cannot find the file specified:
...pylupdate6.exe
...pylupdate6.exe.deleteme'

I think this solution will work for any python package

Open a command shell run as administrator and run it again:

pip3 install --upgrade --force-reinstall PyQt6
Collecting PyQt6
...
Successfully installed PyQt6-6.4.1 PyQt6-Qt6-6.4.2 PyQt6-sip-13.4.1

If you want to re-download the packages instead of using the files from your pip cache, then use:

pip install --force-reinstall --no-cache-dir

Tuesday, January 24, 2023

Python 3.8.10 : My colab tutorials - part 029.

Colab from google is a great tool when you want to write equations. I show a simple example with LaTeX formula with this colab notebook named catafest_034.

Python : Fix DLL load failed while importing ...

This error DLL load failed while importing ... can have many causes like conflicts with the already installed packages, and also it can break your current environment.

>>> import PyQt6
>>> from PyQt6.QtCore import QUrl
Traceback (most recent call last):
  ...
ImportError: DLL load failed while importing QtCore: The specified module could not be found.

You can see I used to reinstall the PyQt6 python package with this argument --ignore-installed:

pip3 install PyQt6 --user --ignore-installed
Collecting PyQt6
  ...
Installing collected packages: PyQt6-Qt6, PyQt6-sip, PyQt6
  WARNING: The scripts pylupdate6.exe and pyuic6.exe are installed in
  ...
  which is not on PATH.
  Consider adding this directory to PATH or, if you prefer to suppress this warning, use --no-warn-script-location.
Successfully installed PyQt6-6.4.0 PyQt6-Qt6-6.4.2 PyQt6-sip-13.4.0

The --ignore-installed option for the pip package manager was first introduced in version 6.0, which was released in April 2014.

The old install give me this error and when I try to use I got this:

>>> from PyQt6 import *
>>> dir(PyQt6)
['__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__path__', '__spec__']

Now after I reinstall with this option the result is good:

>>> import PyQt6
>>> from PyQt6 import QtCore
>>> dir(PyQt6)
['QtCore', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__path__', '__spec__', 'sip']
>>> from PyQt6.QtCore import QUrl