Python List Comprehensions

A lightning talk on Python list comprehensions for Grow Beyond with Google.

Transcript

1. Python List
   Comprehensions
   

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2. ‘Traditional’ way
   Constructing a list of squares of even numbers:
   squares_of_evens = []
   # range(10) -> [0,1,2,3,4,5,6,7,8,9]
   for n in range(10):
   if n%2==0:
   squares_of_evens.append(n*n)
   print squares_of_evens #[0, 4, 16, 36, 64]
   It works - but ugly and slow!
   

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3. Construct lists in a concise way
   General syntax:
   new_list = [new_item for item in input_list]
   new_list = [new_item for item in input_list if some_condition]
   Squares of even numbers:
   squares_of_evens = [n*n for n in range(10) if (n%2 == 0)]
   print squares_of_evens #[0, 4, 16, 36, 64]
   

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4. Thanks!
   

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