Add first session of 2021

meetings/2021/session_01_what_I_which_I_had_known_when_I_started_learning_how_to_code/2021-01-19.md

+# EMBL Python User Group - 2021-01-19
+
+## What I wish I had known when I started learning how to code
+
+* Learn how to ask programming questions:
+  * http://www.catb.org/~esr/faqs/smart-questions.html
+
+* Find a community of like minded coders
+  * EMBL Bio-IT chat #python
+  * IRC Freenode #python #pydata #bioinformatics #django
+  * Reddit #python
+  * Stackoverflow
+  * ...
+
+* (ana)conda will mostly save you sanity
+  * but pip install is pretty great nowadays
+  * If conda is too slow resolving dependencies have a look at https://github.com/mamba-org/mamba
+
+* Virtual environments
+  * conda / anaconda
+  * venv and virtualenv
+
+* Use an editor that helps you
+  * Syntax highlight
+  * Code completion
+  * Linter - flags errors or potential problems
+  * Has debugging abilities
+  * [VSCode](https://code.visualstudio.com/) - great for multiple languages, remote interaction (port-forwarding, ...), integrates jupyter notebooks
+  * [PyCharm](https://www.jetbrains.com/pycharm/) - also great option, very complete and professional grade IDE (Integrated Desktop Editor) - see [Professional vs Community (free) edition](https://www.jetbrains.com/pycharm/download)
+  * [Atom](https://atom.io/) - versatile and modular editor - used as base for other editors (e.g. [Juno](https://junolab.org/) for the Julia programming language)
+  * [GitPod](https://www.gitpod.io/).io - Online VSCode-like experience - same environment for everyone needing only a browser to get started - see also [GitPod browser extension](https://www.gitpod.io/docs/browser-extension/)
+
+* Don't worry about performance, readability is more important
+  * Be kind to your future self
+  * Consider if the more verbose option is more readable than the very concise one
+    ```python
+    output = {x:y for x in ones for y in twos}
+    ```
+    vs
+    ```python
+    output = {}
+    for x in ones:
+        for y in twos:
+           output[x] = y
+    ```
+  * Use functions, leave classes for later.
+  * text is not text -> And why do we need Bytes and Strings
+  * Use descriptive names
+  * Follow a code style (e.g. PEP8, Google Python Style)
+    * A linter will help you (flake8, pylint, ...)
+    * Use docstrings - follow sphinx or numpy style - avoid mixing styles
+  * Comment/document things!! (in addition to docstrings)
+    * Describe **why** not **what** is happening
+      * Bad: If we don't have a zero here the code takes 10 times longer to finish
+      * Better: This function accepts 0 or 1 and 1 is the slower version
+      * Great: Valid values 0, 1: when 1, the code checks if planets are aligned before beginning ritual, this reduces failures but increases execution time.
+  * Tests are great, but they might be hard to get right
+    Doctests are a great alternative which serves as documentation too e.g:
+
+    ```python
+    def divide_and_conquer(values, position):
+        """Breaks the list of values in to two at the specified position
+
+        >>> divide_and_conquer([5, 6, 7], 2)
+        ([5, 6], [7])
+        >>> divide_and_conquer([1, 2], 10)
+        ([1, 2], [])
+        >>> divide_and_conquer([1, 2], 0)
+        ([], [1, 2])
+        """
+        return values[:position], values[position:]
+    ```
+    * pytest - great test runner