Counting occurrence of non-specified values from 2d array in Python

Question

I've got a similar array:

[['foo', 9283], ['bar', 7172], ['bar', 9890], ['foo', 2291], ['fuubar', 8291]]

I want to count the same values in list[i][0], without specifying what string I want to find. Examples I've found on the Internet are either about 1D arrays or with specification. If I had a 1D array that would be extremely simple:
Example 1 with specifying the value (1)

[1, 2, 3, 4, 1, 4, 1].count(1)
3

Example 2 without specyifying what to look for

>>> from collections import Counter
>>> z = ['blue', 'red', 'blue', 'yellow', 'blue', 'red']
>>> Counter(z)
Counter({'blue': 3, 'red': 2, 'yellow': 1})

My desired output would be similar. Given my example, I want to know how many times does 'foo' occur, 'bar' occurs, 'fuubar' occurs. But how do I do this with a 2D array?

Note that 0091 is not a valid literal anymore. It used to be a literal octal. — Cory Kramer
– Cory Kramer, Commented Feb 16, 2015 at 13:38

horns · Accepted Answer · 2015-02-16 13:37:29Z

1

Use generator expression to extract the items you want to count:

>>> from collections import Counter
>>> l = [['foo', 9283], ['bar', 7172], ['bar', 9890], ['foo', 91], ['fuubar', 8291]]
>>> Counter(item[0] for item in l)
Counter({'foo': 2, 'bar': 2, 'fuubar': 1})

answered Feb 16, 2015 at 13:37

horns

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Mark R. · Accepted Answer · 2015-02-16 13:37:06Z

1

Counter([z[0] for z in [['foo', 9283], ['bar', 7172], ['bar', 9890], ['foo', 91], ['fuubar', 8291]]])

answered Feb 16, 2015 at 13:37

Mark R.

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Padraic Cunningham · Accepted Answer · 2015-02-16 13:46:06Z

1

You can unpack:

Counter(s for s, _ in l))

Or for a functional approach:

from operator import itemgetter
print(Counter(map(itemgetter(0), l)))

answered Feb 16, 2015 at 13:46

Padraic Cunningham

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