Python packages

On linux , python packages are stored in

/usr/local/lib/pythonx.xx/dist-packages

These are packages installed on your local system.

Create virtual environment

To create a virtual environment for packages , do.

``

Put dictionary keys in list

a = {'key1' : 'value1', 'key2': 'value2' }  

a_list = [*a] # Putting asterisk key before dict gets all keys

print(a_list)

['key1', 'key2']

Print out dictionary values

a = {'key1' : 'value1', 'key2': 'value2' }  

Detect OS platform

import sys


if sys.platform.startswith("linux"):
    print('on linux')

elif sys.platform.startswith("win32"):
    print('on windows')

Print out parent directory of Path object

import pathlib

path = pathlib.Path('/home/user/Downloads')

print(path.parent)

OUTPUT :

/home/user

Determine if you are in a certain directory , for example “Downloads”

import pathlib 

path = pathlib.Path('/home/user/Downloads')

if pathlib.PurePath(path).match("Downloads") : 
    print('path leads to /home/user/Downloads')

Basic beautiful soup example

from bs4 import BeautifulSoup

html_doc = requests.get(url)

soup = BeautifulSoup(html_doc, 'html.parser')

Search by tag in BeautifulSoup

    for x in soup.find_all('p'):
        print(x)
    

Search for other content inside a div in BeautifulSoup

For exmple , searching for all paragrap tags inside a div with an id of “content-div”

x = soup.find('div', {'id': 'content-div'}).findAll('p')

Remove all packages installed by pip

pip freeze | xargs pip uninstall -y

PyQt notes

using the loadUi class automatically creates python objects by using their ObjectName in QtDesigner

• The QFileDialog is actually in the QtWidgets class and not the QtGui class like in earlier versions

Print out string as lower case

example_str = "Hello"

>>> example_str.lower() 

"hello"

Create documentation with pydoc

python3 -m pydoc modulename

remember to not put the *.py file extension at the end