Python for Official Statistics: Key Points

Introduction

Python is an interpreted language.
Code is commonly developed inside an integrated development environment.
A typical Python workflow uses base Python and additional Python packages developed for statistical programming purposes.
In-line and external documentation helps ensure that your code is readable.
You can find help through the built-in help function and external resources.

Basic data types in Python include integers, strings, and floating-point numbers.
Use variable = value to assign a value to a variable in order to record it in memory.
Variables are created on demand whenever a value is assigned to them.
Use print(something) to display the value of something.
Use # some kind of explanation to add comments to programs.
Built-in functions are always available to use.

Lists can contain any Python object including other lists
Lists are ordered i.e. indexed and can therefore be sliced by index number
Unlike strings and integers, the values inside a list can be modified in place
A list which contains other lists is referred to as a nested list
Dictionaries behave like unordered lists and are defined using key-value pairs
Dictionary keys are unique
A dictionary which contains other dictionaries is referred to as a nested dictionary
Values inside nested lists and dictionaries can be accessed by an additional index

Use for variable in sequence to process the elements of a sequence one at a time.
The body of a for loop must be indented.
Use len(thing) to determine the length of something that contains other values.
Use if condition to start a conditional statement, elif condition to provide additional tests, and else to provide a default.
The bodies of the branches of conditional statements must be indented.
Use == to test for equality.
X and Y is only true if both X and Y are true.
X or Y is true if either X or Y, or both, are true.
Zero, the empty string, and the empty list are considered false; all other numbers, strings, and lists are considered true.
True and False represent truth values.

Define a function using def function_name(parameter).
The body of a function must be indented.
Call a function using function_name(value).
Numbers are stored as integers or floating-point numbers.
Variables defined within a function can only be seen and used within the body of the function.
Variables created outside of any function are called global variables.
Within a function, we can access global variables.
Variables created within a function override global variables if their names match.
Use help(thing) to view help for something.
Put docstrings in functions to provide help for that function.
Specify default values for parameters when defining a function using name=value in the parameter list.
Parameters can be passed by matching based on name, by position, or by omitting them (in which case the default value is used).
Put code whose parameters change frequently in a function, then call it with different parameter values to customize its behavior.