- Basic Python Cheat Sheet
- Best Python Cheat Sheet Github
- Python Cheat Sheet Github
- Python Cheat Sheet Pdf
The text of the quick referance sheets comes from the IPython%quickref magic command. To download an image below, right click on the link and select 'Save Link As'. Basic Help.svg Download Magic Help.svg Download For more details of magic usage see the Built-in magic commands page in IPython's documentation. Git Cheat Sheets. Reference sheets covering Git commands, features, SVN migrations, and bash. Available in multiple languages. Beginner’s Python Cheat Sheet - Dictionaries Focuses on dictionaries: how to build and modify a dictionary, access the information in a dictionary, and loop through dictionaries in a variety of ways. Includes sections on nesting lists and dictionaries, using dictionary comprehensions, and more. Collection 10 Tensorflow Cheat Sheets Every ML Engineer Must Download, Print, and Study Read More ». This is a really great cheat sheet written by Patrick on Github! He shows examples and syntax. This is a great sheet for all Tensorflow learners!! 11 Python Cheat Sheets Every Python. Matplotlib 3.1 cheat sheet. Matplotlib tries to make easy things easy and hard things possible. You can generate plots, histograms, power spectra, bar charts, errorcharts, scatterplots, etc., with just a few lines of code.
A virtualenv is one of the first things a Python programmer learns about. This blog post describes what it is, how to set it up, and examples of some concrete use cases.
What is a virtualenv?
A virtualenv is a way of having separate Python environments. It allows you to have different environments for Python 2 and Python 3 and the 3rd party package dependencies to go along with that environment.
Quickstart
Run the following commands to create and activate your first virtualenv
virtualenv for Python3
virtualenv for Python2
Verify it’s working
You should see the command line now starting with (venv). This means that the virtualenv is active.
Run which python and it should point to a Python executable inside the virtualenv at venv/bin/python
Quickstart Explanation
First get pip. pip, which stands for “Pip Installs Packages”, is the Python ecosystem’s package installer. If it is not already installed. This can be done using the linked instructions, or with this command.
If you already have pip or just want to check, run this command to check and output all installed 3rd party packages:
If you currently have other 3rd party packages, and want to clean up the gloal dependencies, then run this command to remove all 3rd party packages:
This is my prefered configuration. To only have virtualenv as the single global 3rd party package. Other packages are local to the virtualenv.
Now, install virtualenv globally.
Check what version of Python is the default version.
On my machine, the previous command returned Python 2.7.14. So, when I create a virtualenv this will be the default Python version, unless another version is specified.
Create a new virtualenv
Why is it named venv?
By convention, the name venv is used as the name of the virtualenv, but any name can be used.
Now, activate the virtualenv
venv, the name of the virtualenv should show at the start of the command line prompt.
If you run pip freeze at this point, there should be no output because this is a new Python environment. The global virtualenv that was just installed should not appear in the output.
At this point, any 3rd party Python package can be installed, just like virtualenv was installed globally, and as long as the virtualenv is active, it will be private to that virtualenv.
To deactivate the virtualenv, run:
CheatSheet
Here are some use cases and common commands.
Create a virtualenv in Python3
The venv standard library package is available as of Python 3.3 and can be used to create a virtualenv
virtualenv with a specific version of Python
This will create a virtualenv in Python 3.5
Access the virtualenv without it being active
By using the path to the Python executable inside of the venv, the virtualenv and all of it’s 3rd party packages will be loaded:
virtualenv with cron
Basic Python Cheat Sheet
Include global Python packages when creating a virtualenv
Delete a virtualenv
Store copy of Python package versions
This is done by convention in a file called requirements.txt
Install all packages from requirements.txt
This command would be used when running another projects code, to install all dependencies of the project.
Best Python Cheat Sheet Github
Conclusion
virtualenv has been very useful. Now days, with Docker, and containers, they’re not always necessary, but if you’re developing locally and have multiple Python projects, they’re a must. You won’t get package conflicts, and can maintain different Python version and environments.
Any questions?
Thank you for reading. If you have any questions or anything that I can add, please let me know. Thanks.
A quick reference to Python
Created on: 2019-09-29
Tag: cheat_sheet
Warning
under heavy construction and not well organized
(source: http://stackoverflow.com/a/34863581/5350059)
OR:
source: https://stackoverflow.com/a/34964610
(source: http://stackoverflow.com/a/1557584/5350059)
(source: http://stackoverflow.com/a/42641792/5350059)
(source: http://stackoverflow.com/a/6797990/5350059)
don't forget to import os
(source: http://stackoverflow.com/a/1274465/5350059)
(source: http://stackoverflow.com/a/32508983/5350059)
(source: http://stackoverflow.com/a/31923407/5350059)
(source: http://stackoverflow.com/a/15824216/5350059)
(source: http://stackoverflow.com/a/39452138/5350059)
(source: http://stackoverflow.com/a/8384838/5350059)
(source: http://stackoverflow.com/q/7961499/5350059)
(source: http://stackoverflow.com/a/25710057/5350059)
(source: https://stackoverflow.com/a/983382)
(source: https://stackoverflow.com/a/1051266/5350059)
Python Cheat Sheet Github
(source: https://www.facebook.com/groups/pythonbd/permalink/1182034515231297/)
(source: https://stackoverflow.com/a/73673/5350059)
(source: https://www.geeksforgeeks.org/send-mail-attachment-gmail-account-using-python/)
to see the package install location:
(source: https://stackoverflow.com/a/45309460/5350059)
to build regex with variable or as string:
source: https://stackoverflow.com/a/6931070/5350059
to find all string that matches a regex:
source: https://stackoverflow.com/a/4697884/5350059
to repeat string:
example:
source: https://stackoverflow.com/a/17183278/5350059
OR
use this:
source: https://stackoverflow.com/a/43828469/5350059
to access command line arguments:
Note
sys.argv is a list where sys.argv[0] is the program name.
source: https://stackoverflow.com/a/4033743/5350059
to check if argument is empty:
source: https://stackoverflow.com/a/2194187/5350059
to check if a list is empty:
source: https://stackoverflow.com/a/53522/5350059
to get full path from file and directory name:
source: https://stackoverflow.com/a/7133204/5350059
to iterate over files in a directory:
source: https://stackoverflow.com/a/10378012/5350059
Django supports bash auto-completion. for this first download auto-completion script:
Modify bashrc to add auto-completion script:
Reload latest bashrc:
source: http://www.indjango.com/ubuntu-django-bash-auto-completion/
to install package from inside python shell:
Python Cheat Sheet Pdf
source: https://stackoverflow.com/a/57594338/5350059
to print bold text:
We can do more tricks:
source: https://stackoverflow.com/a/17303428/5350059
to get all object attributes of a object:
source: https://stackoverflow.com/a/6886507/5350059
to beautify JSON in Python:
source: https://stackoverflow.com/a/9105132/5350059
to create a django secret key with bash:
Kept also in the Bash Cheat Sheet as it is relevant.
source: How to generate a random string?
to read dictionary in pandas:
source: pandas.DataFrame.from_dict
to print a column in pandas:
Output:
source: Display/Print one column from a DataFrame of Series in Pandas
to see heading columns in pandas:
source: pandas.DataFrame.head
to do a dot matrix of two numpy array:
source: NumPy v1.17 Manual: numpy.dot
to convert character to integer:
to convert integer to character:
source: https://stackoverflow.com/a/704160/5350059
to check if string is upper case:
source: https://stackoverflow.com/a/3669033/5350059
source: https://stackoverflow.com/a/21890604