How to sort Counter by value - python

Question

Other than doing list comprehensions of reversed list comprehension  is there a pythonic way to sort Counter by value  If so  it is faster than this    gt  gt  gt  from collections import Counter  gt  gt  gt  x   Counter   a  5   b  3   c  7    gt  gt  gt  sorted x    a    b    c    gt  gt  gt  sorted x items       a   5     b   3     c   7    gt  gt  gt    l k  for k l in sorted   j i  for i j in x items         b   3     a   5     c   7    gt  gt  gt    l k  for k l in sorted   j i  for i j in x items     reverse True      c   7     a   5     b   3

User · Answer

More general sorted  where the key keyword defines the sorting method  minus before numerical type indicates descending     gt  gt  gt  x   Counter   a  5   b  3   c  7    gt  gt  gt  sorted x items    key lambda k  -k 1      Ascending    c   7     a   5     b   3

User · Answer

Use the Counter most common   method  it ll sort the items for you    gt  gt  gt  from collections import Counter  gt  gt  gt  x   Counter   a  5   b  3   c  7    gt  gt  gt  x most common      c   7     a   5     b   3     It ll do so in the most efficient manner possible  if you ask for a Top N instead of all values  a heapq is used instead of a straight sort    gt  gt  gt  x most common 1     c   7     Outside of counters  sorting can always be adjusted based on a key function   sort   and sorted   both take callable that lets you specify a value on which to sort the input sequence  sorted x  key x get  reverse True  would give you the same sorting as x most common    but only return the keys  for example    gt  gt  gt  sorted x  key x get  reverse True    c    a    b     or you can sort on only the value given  key  value  pairs    gt  gt  gt  sorted x items    key lambda pair  pair 1   reverse True     c   7     a   5     b   3     See the Python sorting howto for more information

User · Answer

A rather nice addition to  MartijnPieters answer is to get back a dictionary sorted by occurrence since Collections most common only returns a tuple  I often couple this with a json output for handy log files    from collections import Counter  OrderedDict  x   Counter   a  5   b  3   c  7   y   OrderedDict x most common      With the output   OrderedDict    c   7     a   5     b   3         c   7      a   5      b   3

User · Answer

Yes    gt  gt  gt  from collections import Counter  gt  gt  gt  x   Counter   a  5   b  3   c  7     Using the sorted keyword key and a lambda function    gt  gt  gt  sorted x items    key lambda i  i 1      b   3     a   5     c   7    gt  gt  gt  sorted x items    key lambda i  i 1   reverse True     c   7     a   5     b   3     This works for all dictionaries  However Counter has a special function which already gives you the sorted items  from most frequent  to least frequent   It s called most common      gt  gt  gt  x most common      c   7     a   5     b   3    gt  gt  gt  list reversed x most common        in order of least to most    b   3     a   5     c   7     You can also specify how many items you want to see    gt  gt  gt  x most common 2     specify number you want    c   7     a   5

[python] How to sort Counter by value? - python

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