Counter() most_common()

1 not only can count the number of occurrences of the elements in list, you can also count on the elements of str

# The Collections package Counter for statistical str list of elements in the number of occurrences 
from the Collections Import Counter
a = [1,1,2,3,4,5,6,6,6]
B = Counter (a)
 # outputs a class a number of occurrences of each element, and the descending order according to the number of occurrences 
Print (B)
 # output element 5 occurrences of 
Print (B [5 ])
 # output Occurrences the three (element number) pair, and the type is List 
Print (b.most_common (. 3 ))
 # Counter (. 6 {:. 3,. 1: 2, 2:. 1,. 3:. 1,. 4:. 1,. 5:. 1 }) 
# 1 
# [(6, 3), (1, 2), (2, 1)]


# Directly as the output element by the number of descending sort occur with most_common () object of the Counter (a) into a List, facilitate iterative 
Print ([Item for items, C in Counter (a) .most_common () for Item in [items] * C])
 # [. 6,. 6,. 6,. 1,. 1, 2,. 3,. 4,. 5]

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