# Advanced Python 🐍

###### tags: `yotta` `python`

[TOC]

## Project Setup & management

### Install Miniconda

#### Mac

brew install miniconda

# adds conda installation in your PATH
conda init bash

#### Linux (Ubuntu)

# you might need to sudo these commands
wget https://repo.anaconda.com/miniconda/Miniconda3-latest-Linux-x86_64.sh
chmod +x Miniconda3-latest-Linux-x86_64.sh
bash Miniconda3-latest-Linux-x86_64.sh -p $HOME/miniconda3

### Create your Conda environment
Why use virtual environment ?
- To separate any python install that is already on your system with the ones that you will be using on your projects
- reproducibility
- completely isolate your projects from one another

# create a new virtual environment named 'myenv' 
# with the latest python 3 available
conda create --name myenv python=3

# activate it
conda activate myenv

# you can see that the python which is called 
# within this environment is the one installed with it
which python3
# /.../miniconda/base/envs/myenv/bin/python3

which pip
# /.../miniconda/base/envs/myenv/bin/pip

# to see its version
python --version

# to get info on your current environment 
# (version, location...)
conda info

# to list all virtual environments on your machine
conda info --envs

# to deactivate your current environment
conda deactivate

# to delete your environment 'myenv'
conda remove --name myenv --all

### Install packages

# 2 ways to do it
pip install pandas
conda install pandas

# to see what packages are in your current environment 
# (and which versions)
conda list

### Alternative: venv

# create virtual environment myenv
python -m venv .myenv

# activate myenv
source .myenv/bin/activate

# check wich version are used
which python
which pip

# deactivate current environment
deactivate

### misc.

# In the body of the script, after imports, def...
if __name__ == '__main__':
# __name__ is a context variable which is
# '__main__' if called directly (not via import)
# Split current line : \ (to be avoided)


# When you need a loop but don't need the actual counter variable
for _ in range(n):
    ...

### lambda

# Bad usage example of a lambda
is_curzon = lambda n: not (1 + 2**n) % (1 + 2*n) 

# Right usage example for a lambda
def apply(func):
    x = 2
    func(x)
apply(lambda x: x*2)

# Another exemple:
def mutate_dict(f,d):
    for k, v in d.iteritems():
        d[k] = f(v)
my_dictionary = {'a':1, 'b':2}
mutate_dict(lambda x: x+1, my_dictionary)

### generators

# Enumerate : generator, generates tuple on the fly
enumerate("Hello")

# Useful for cases such as:
for i, char in enumerate(message):
    ...
# i is going to be the number (position) and
# char the actual character at that positon

# To store it in memory (i.e. store it into an iterator)
list(enumerate("Hello"))
set(enumerate("Hello"))

# If you need to iterate on multiple iterators at the same time :
number_list = [1, 2, 3]
str_list = ['one', 'two', 'three', 'four']
for x, y in zip(number_list, str_list):
    print(x, x)
# Stops at the shortest iterator, here number_list (3)
# Works with more than 2 iterators