Get count of a given item inside a list (without using numpy)

user_14445865 0
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I'm trying to figure out how to count the frequency of each unique number in the below array, ranging from 1 - 17:

x3 = [ 8 12 10  9  6  6  5 11  9 10  4 12 10  7  7  7  7  9  8  7  9  6  7  8
  8 10  7  9  9  5  9  7  5 12 12 10  7  6  9  8  6  8  5 11  7  9  7  9
  9  7 12 10 12 11  9 11  6  7  5  8  8  7 10  8  7  9  6 10  6 13]

Using numpy, this was done by [np.equal(x3, i).sum() for i in range (1,18)]

What is the best alternative way to do this without numpy?

frequency list numpy python
2 Answers

The standard collections module can do it

import collections
x3 = [1,1,2,2]
counts = collections.Counter(x3)
print(counts)
user_6420700

You can also use a dictionary

numList = [1,2,3,1,2,3,4,5,3,4,5,6,7,8,7,6,2]
freq = dict()
for num in numList:
    if num in freq.keys():
        freq[num] += 1
    else:
        freq[num] = 1

print(freq)
{1: 2, 2: 3, 3: 3, 4: 2, 5: 2, 6: 2, 7: 2, 8: 1}
user_144459180
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