Initialise a list to a specific length in Python

Question

How do I initialise a list with 10 times a default value in Python   I m searching for a good-looking way to initialize a empty list with a specific range   So make a list that contains 10 zeros or something to be sure that my list has a specific length

User · Answer

list multiplication works    gt  gt  gt   0    10  0  0  0  0  0  0  0  0  0  0

User · Answer

If the  default value  you want is immutable   eduffy s suggestion  e g   0  10  is good enough   But if you want  say  a list of ten dicts  do not use      10 -- that would give you a list with the same initially-empty dict ten times  not ten distinct ones  Rather  use     for i in range 10   or similar constructs  to construct ten separate dicts to make up your list

User · Answer

In a talk about core containers internals in Python at PyCon 2012  Raymond Hettinger is suggesting to use  None    n to pre-allocate the length you want   Slides available as PPT or via Google  The whole slide deck is quite interesting  The presentation is available on YouTube  but it doesn t add much to the slides

[python] Initialise a list to a specific length in Python

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