How to unnest a nested list

Question

Possible Duplicate    Making a flat list out of list of lists in Python       I am trying to find an easy way to turn a multi dimensional  nested  python list into a single list  that contains all the elements of sub lists   For example   A     1 2 3 4 5     turns to  A    1 2 3 4 5    or  A     1 2    3 4     turns to  A    1 2 3 4

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itertools provides the chain function for that   From http   docs python org library itertools html recipes   def flatten listOfLists        Flatten one level of nesting      return chain from iterable listOfLists    Note that the result is an iterable  so you may need list flatten

User · Answer

Use reduce function  reduce lambda x  y  x   y  A        Or sum  sum A

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the first case can also be easily done as   A A 0

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Use itertools chain   itertools chain  iterables   Make an iterator that returns elements from the first iterable until it is exhausted  then proceeds to the next iterable  until all of the iterables are exhausted  Used for treating consecutive sequences as a single sequence   Example  from itertools import chain  A     1 2    3 4    print list chain  A     or better   available since Python 2 6  print list chain from iterable A    The output is   1  2  3  4   1  2  3  4

[python] How to unnest a nested list

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