Python How to remove empty lists from a list

Question

I have a list with empty lists in it   list1                         text    text2        moreText     How can I remove the empty lists so that I get   list2     text    text2    moreText     I tried list remove     but that doesn t work

User · Answer

list1                         text    text2        moreText   list2      for item in list1      if item              list2 append item  print list2    output     text    text2    moreText

User · Answer

You can use filter   instead of a list comprehension   list2   filter None  list1    If None is used as first argument to filter    it filters out every value in the given list  which is False in a boolean context   This includes empty lists   It might be slightly faster than the list comprehension  because it only executes a single function in Python  the rest is done in C

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I found this question because I wanted to do the same as the OP  I would like to add the following observation   The iterative way  user225312  Sven Marnach    list2    x for x in list1 if x    Will return a list object in python3 and python2   Instead the filter way  lunaryorn  Imran  will differently behave over versions   list2   filter None  list1    It will return a filter object in python3 and a list in python2  see this question found at the same time   This is a slight difference but it must be take in account when developing compatible scripts   This does not make any assumption about performances of those solutions  Anyway the filter object can be reverted to a list using   list3   list list2

User · Answer

Adding to the answers above  Say you have a list of lists of the form   theList      a   b                   d   e   f   g           and you want to take out the empty entries from each list as well as the empty lists you can do   theList    x for x in theList if x           remove empty lists for i in range len theList        theList i    list filter None  theList i     remove empty entries from the lists   Your new list will look like  theList      a   b     d   e   f   g

User · Answer

Try  list2    x for x in list1 if x          If you want to get rid of everything that is  falsy   e g  empty strings  empty tuples  zeros  you could also use  list2    x for x in list1 if x

User · Answer

Calling filter with None will filter out all falsey values from the list  which an empty list is   list2   filter None  list1

User · Answer

gt  gt  gt  list1                         text    text2        moreText    gt  gt  gt  list2    e for e in list1 if e   gt  gt  gt  list2   text    text2    moreText

User · Answer

A few options   filter lambda x  len x   gt  0  list1     Doesn t work with number types filter None  list1     Filters out int 0  filter lambda x  x  0 or x  list1    Retains int 0    sample session   Python 2 7 1  r271 86832  Nov 27 2010  17 19 03   MSC v 1500 64 bit  AMD64   on win32 Type  help    copyright    credits  or  license  for more information   gt  gt  gt  list1                         text    text2        moreText    gt  gt  gt  filter lambda x  len x   gt  0  list1    text    text2    moreText    gt  gt  gt  list2                         text    text2        moreText   0 5  1  -1  0   gt  gt  gt  filter lambda x  x  0 or x  list2    text    text2    moreText   0 5  1  -1  0   gt  gt  gt  filter None  list2    text    text2    moreText   0 5  1  -1   gt  gt  gt

User · Answer

a     1  aa  3 12  a   b   c   s          1  aa  7 80  d   g   f       9 None 11 12 13 14 15  k     b    for lng in range len a           if len a lng   gt  1  b append a lng   a b print a    Output     1  aa  3 12  a   b   c   s    1  aa  7 80  d   g   f       9 None 11 12 13 14 15  k

[python] Python: How to remove empty lists from a list?

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