Expanding stack with list comprehensions

Asked May 23 '20 at 12:21

Active May 23 '20 at 12:27

Viewed 15 times

How to explain that list comperhensions expression does not work (python 3.8.2 32bit env):

def perfect_squares(max_psqare):
   psqares = [0]
   return [psqares.append(psqares[-1] + 2 * i - 1) for i in range(1, int(max_psqare ** 0.5) + 1)]

in contrast to:

def perfect_squares(max_psqare):
   psqares = [0]
   max_base = int(max_psqare ** 0.5)
   for i in range(1, max_base + 1):
      psqares.append(psqares[-1] + 2 * i - 1)
   return psqares

First one gives array of None values? Comperhension expression does not have access to psqares stack?

edited May 23 '20 at 12:27

Dimitris Fasarakis Hilliard

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asked May 23 '20 at 12:21

lissajous

2

`list.append` returns `None`. Your list comprehension is gathering the `None`s resulting from each append. Your `psqares` has the values. – Dimitris Fasarakis Hilliard May 23 '20 at 12:27
@DimitrisFasarakisHilliard, you are right. Thank you! – lissajous May 23 '20 at 12:30

Expanding stack with list comprehensions

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