The most efficient way to remove first N elements in a list

Question

I need to remove the first n elements from a list of objects in Python 2 7  Is there an easy way  without using loops

User · Answer

l    1  2  3  4  5  del l 0 3    Here 3 specifies the number of items to be deleted    This is the code if you want to delete a number of items from the list  You might as well skip the zero before the colon  It does not have that importance  This might do as well   l    1  2  3  4  5  del l  3    Here 3 specifies the number of items to be deleted

User · Answer

You can use list slicing to archive your goal   n   5 mylist    1 2 3 4 5 6 7 8 9  newlist   mylist n   print newlist   Outputs    6  7  8  9    Or del if you only want to use one list   n   5 mylist    1 2 3 4 5 6 7 8 9  del mylist  n  print mylist   Outputs    6  7  8  9

User · Answer

Python lists were not made to operate on the beginning of the list and are very ineffective at this operation   While you can write   mylist    1  2  3  4  mylist pop 0    It s very inefficient     If you only want to delete items from your list  you can do this with del   del mylist  n    Which is also really fast   In  34     timeit help range 10000  while help      del help  1000           10000 loops  best of 3  161   s per loop     If you need to obtain elements from the beginning of the list  you should use collections deque by Raymond Hettinger and its popleft   method   from collections import deque  deque   f    g    h    i    j      gt  gt  gt  d pop                              return and remove the rightmost item  j   gt  gt  gt  d popleft                          return and remove the leftmost item  f    A comparison   list   pop 0   In  30     timeit          help range 10000           while help               help pop 0           100 loops  best of 3  17 9 ms per loop   deque   popleft    In  33     timeit help deque range 10000   while help      help popleft            1000 loops  best of 3  812   s per loop

User · Answer

Try to run this code   del x  N

[python] The most efficient way to remove first N elements in a list?

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