Python Reverse Engineer List Comprehensions

Question

Hello I am new to Python and Stackoverflow so please bear with me. I just recently discovered list comprehensions and wanted to "reverse engineer" a specific code to understand it better. In other words, how would the following code look in the regular block format:

    return [variable[i:i+10] for i in range(0,100,10)]

Answer 1

http://treyhunner.com/2015/12/python-list-comprehensions-now-in-color/ is a great resource, but in general, comprehensions in Python are of the form:

<expression> for <value> in <iterable> [if <criteria>]

So breaking out your example, we have:

• An expression: variable[i:i+10]
• A value i
• the iterable range(0,100,10)
• no criteria

The "expanded" form is:

result = []
for <value> in <iterable>:
    [if <criteria>:]
        result.append(<value>)

(generator, dict, and set comprehensions are all similar)

So taking your example, we get:

result = []
for i in range(0,100,10):
    result.append(variable[i:i+10])
return result