[PYTHON] List comprehension

Summarize the content notation of python. For myself for learning.

1. Comprehension notation Write what was written separately for processing and for statement in this way as in the last line. Describe the process you want to perform before the for statement.
1. How to write comprehension notation using if statement In the comprehension notation, if you want to use an if statement, write it after the part you want to use. Note that in the case of a statement that also includes else, both must be written before the for statement.
1. Let's make a two-dimensional list one-dimensional. This description contains two for statements, but since this execution is executed from the beginning, it will be described later. Unless it is nested, it will be expanded in order
Nested inclusion notation. This comprehension is nested. If it is nested, in this figure, it is executed from for i in range (4) and the process [row [i] for row in matrix] is performed. Also, the zip () function allows you to process multiple values at once.
Dictionary type comprehension The dictionary-type comprehension covers the whole with curly braces. The description of only the if statement is described afterwards. When describing both if and else, describe with a prefix. Since it is a dictionary type, write a judgment formula for both key and value. There is also a way to write using zip as described later. You can also describe the contents of the set by writing without a colon.