1

I have a csv file that I process this way. The csv containing just numbers is such:

1, 5, 6, 8, 45, 56

2, 6, 34, 42, 56, 98

1, 5, 6, 8, 45, 56

...

import csv

numbers = []

with open('example.csv', newline='') as f:
    reader = csv.reader(f)
    for row in reader:
        numbers.append(row)        
               
print(numbers)

output:

[[1, 5, 6, 8, 45, 56], [2, 6, 34, 42, 56, 98], [1, 5, 6, 8, 45, 56]]

How can I make it print the most frequently occurring lists? For example: 1, 5, 6, 8, 45, 56 2 times in list?

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  • using the .count() method perhaps? Commented Jun 26, 2021 at 12:44

4 Answers 4

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2

You can use the Counter class from collections. It can't take lists of lists directly, but by converting the inner lists to tuples you can count them:

from collections import Counter

lst = [[1, 5, 6, 8, 45, 56], [2, 6, 34, 42, 56, 98], [1, 5, 6, 8, 45, 56]]
Counter(tuple(i) for i in lst).most_common(1)

yields the most common list and how many times it occured:

[((1, 5, 6, 8, 45, 56), 2)]

Counter have several other useful functions when it comes to counting, and it is very performant.

The docs for Counter

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0

Use count row when you are appending numbers

import csv

numbers = []
max_occurance_count=0

with open('example.csv', newline='') as f:
    reader = csv.reader(f)
    for row in reader:
        numbers.append(row)        
        if numbers.count(row) > max_occurance_count:
            max_occurance_count=numbers.count(row)
            max_occured_row = row
print(numbers)
print (max_occured_row)
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0 
import csv

numbers = []

with open('example.csv', newline='') as f:
    reader = csv.reader(f)
    for row in reader:
        numbers.append(row)    

a = [] #empty list
for i in numbers:
    a.append(numbers.count(i))   
numbers[a.index(max(a))]

Output:

[1, 5, 6, 8, 45, 56]
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0

If you don't want to use Counter, you can do the following (l is your list):

d={tuple(i):l.count(i) for i in l}
d=sorted(d, key=lambda x: d[x], reverse=True)

res=list(d[0])

print(res)

#[1, 5, 6, 8, 45, 56]
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