Python：计算字典的重复值

Question

I have a dictionary as follows:

dictA = { ('unit1','test1') : 'alpha' , ('unit1','test2') : 'beta', ('unit2','test1') : 'alpha', ('unit2','test2') : 'gamma' , ('unit3','test1') : 'delta' , ('unit3','test2') : 'gamma'   }

How can I count the number of repeating values per each test independent of units?

ie

in 'test1' there is 2x 'alpha', 1x 'delta'

in 'test2' there is 1x 'beta', 2x 'gamma'

Any inputs?

Many Thanks.

Answer 1

In Python 2.7 or 3.1 or above, you can use collections.Counter :

from collections import Counter
counts = Counter((k[1], v) for k, v in dictA.iteritems())
print(counts)

prints

Counter({('test1', 'alpha'): 2, ('test2', 'gamma'): 2, ('test2', 'beta'): 1, ('test1', 'delta'): 1})