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Clarify Counter() docs.

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Raymond Hettinger 2009-02-25 22:48:24 +00:00
parent e3bc0eff25
commit a665853bab
1 changed files with 6 additions and 8 deletions
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Doc/library/collections.rst
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@ -251,14 +251,12 @@ Common patterns for working with :class:`Counter` objects::
c.most_common()[:-n:-1] # n least common elements c.most_common()[:-n:-1] # n least common elements
c += Counter() # remove zero and negative counts c += Counter() # remove zero and negative counts
Several multiset mathematical operations are provided for combining Several mathematical operations are provided for combining :class:`Counter`
:class:`Counter` objects. Multisets are counters with the restriction objects to produce multisets (counters that have counts greater than zero).
that all counts are at least one. They are like regular sets but are Addition and subtraction combine counters by adding or subtracting the counts
allowed to contain repeated elements. Addition and subtraction combine of corresponding elements. Intersection and union return the minimum and
counters by adding or subtracting the counts of corresponding elements. maximum of corresponding counts. Each operation can accept inputs with signed
Intersection and union return the minimum and maximum of corresponding counts, but the output will exclude results with counts of zero or less.
counts. Each operation can accept inputs with signed counts,
but the output excludes results with counts less than one.
>>> c = Counter(a=3, b=1) >>> c = Counter(a=3, b=1)
>>> d = Counter(a=1, b=2) >>> d = Counter(a=1, b=2)