CODEWITHSUNDEEP
pythonlistcounttuples
tortilla
tortilla

Reputation: 151

Python counting in a tuple list

Basically I have a long list of tuples with author names and a year like here below

a =[('Volozhyn AI', 2007),
 ('Lam KL', 2010),
 ('Boudreau NG', 2006),
 ('Tsuchitani M', 1997),
 ('Zheng LP', 1997),

The list is much longer, I need to count the times a year occurs in this list, so as output list 

b = [(1970, x times),
     (1971, y times), etc

I found that the function Counter counts all the elements in a list and gives a output like that. However, I can't seem to let Counter only count the years. So I have to either make a new list with only the years or another methode. Suggestions?

Upvotes: 0

Views: 130

Answers (2)

Avión
Avión

Reputation: 8386

from collections import Counter

a =[('Volozhyn AI', 2007),
 ('Lam KL', 2010),
 ('Boudreau NG', 2006),
 ('Tsuchitani M', 1997),
 ('Zheng LP', 1997)]

b = (Counter(i[1] for i in a)).items()
print b

Output:

[(2010, 1), (1997, 2), (2006, 1), (2007, 1)]

With i[1] for i in a you get the list with only the years ([2007, 2010, 2006, 1997, 1997]). Then, you count them using Counter and convert it to a list to fit your desired output.

Upvotes: 3

Chandra
Chandra

Reputation: 524

from collections import Counter
Counter(elem[1] for elem in a)

Will give

Counter({1997: 2, 2010: 1, 2006: 1, 2007: 1})

Above code picks up the second element [index 1] in each element and then counts..

Upvotes: 0

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