Using a dictionary to count the items in a list

Question

I m new to Python and I have a simple question  say I have a list of items     apple   red   apple   red   red   pear     Whats the simpliest way to add the list items to a dictionary and count how many times the item appears in the list   So for the list above I would like the output to be     apple   2   red   3   pear   1

User · Answer

L     apple   red   apple   red   red   pear   d       d   setitem   item 1 d get item 0   for item in L  print d    Gives   pear   1   apple   2   red   3

User · Answer

gt  gt  gt  L     apple   red   apple   red   red   pear    gt  gt  gt  from collections import defaultdict  gt  gt  gt  d   defaultdict int   gt  gt  gt  for i in L        d i     1  gt  gt  gt  d defaultdict  lt type  int  gt     pear   1   apple   2   red   3

User · Answer

I always thought that for a task that trivial  I wouldn t want to import anything  But i may be wrong  depending on collections Counter being faster or not   items    Whats the simpliest way to add the list items to a dictionary    stats      for i in items      if i in stats          stats i     1     else          stats i    1    bonus for i in sorted stats  key stats get       print   d    s      stats i   i     I think this may be preferable to using count    because it will only go over the iterable once  whereas count may search the entire thing on every iteration  I used this method to parse many megabytes of statistical data and it always was reasonably fast

User · Answer

How about this   src      one    two    three    two    three    three    result dict   dict     i  src count i   for i in set src        This results in       one   1   three   3   two   2

User · Answer

Simply use list property count   i     apple   red   apple   red   red   pear   d    x i count x  for x in i  print d   output       pear   1   apple   2   red   3

User · Answer

I like   counts   dict   for i in items    counts i    counts get i  0    1    get allows you to specify a default value if the key does not exist

User · Answer

Consider collections Counter  available from python 2 7 onwards    https   docs python org 2 library collections html collections Counter

User · Answer

in 2 7 and 3 1 there is special Counter dict for this purpose    gt  gt  gt  from collections import Counter  gt  gt  gt  Counter   apple   red   apple   red   red   pear    Counter   red   3   apple   2   pear   1

[python] Using a dictionary to count the items in a list

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