How to count how many times values has appeared continuously in array python?

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I have an array of elements x=[9,2,2,2,2,3,4,4,55,55,6,2,2,2,7,0,0], I would like to know how many times a value has shown continuously in this array, using python language. The expected results should be: a=[1,4,1,2,2,1,3,1,2]

The below code shows the duplicated number in x

x=[9,2,2,2,2,3,4,4,55,55,6,2,2,2,7,0,0]
def times_so_far(ls):
    out = [0]*len(ls)
    for i in range(len(ls)):
        out[i] = ls[:i].count(ls[i]) 
    return out
print(times_so_far(x))
duplicates list python
2 Answers

You can use itertools.groupby:

from itertools import groupby
x=[9,2,2,2,2,3,4,4,55,55,6,2,2,2,7,0,0]
out = [len([*group]) for i, group in groupby(x)]
>>> out
[1, 4, 1, 2, 2, 1, 3, 1, 2]
user_66711760

If you'd prefer to use your own function, you could try something like the following:

def count_sequential(ls):
    counts = []
    i = 1
    last_val = ls[0]
    for j in ls[1:]:
        if j != last_val:
            counts.append(i)
            last_val = j
            i = 1
        else:
            i += 1
    counts.append(i)
    return counts
user_39916490
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