Count the amount of lists in a list (nested list) for each length Python

Question

I have a list of lists which contains strings. Like the following:

[['apple', 'pear', 'apple'], ['apple', 'apple'], ['apple', 'pear', 'apple','apple', 'pear', 'apple']]

There are about 2000 lists in this list, all containing a different amount of strings. What I would like to see is how many sublists of certain lengths are in this list. Like the following:

Length 2 strings : 70 lists length 3 strings: 45 lists Etcetera.

A logic way to do this (I think) is to make a loop for a length of desire, and then play this loop for all the lengths that I want the amount of lists of.

I would imagine it being something like this:

def countList(lst, x): 
    count = 0
    for i in range(len(lst)): 
        if x in lst[i]: 
            count+= 1

    return count

x = .....

But I am not sure, because I don't know how to let it count the amount.

If someone could please help me it would be great!!

Could you please make your expected output more clear?

Karthick Mohanraj
– Karthick Mohanraj

2020-05-02 17:41:06 +00:00
Commented May 2, 2020 at 17:41 — Karthick Mohanraj
– Karthick Mohanraj, Commented May 2, 2020 at 17:41

Karl Knechtel · Accepted Answer · 2020-05-02 17:44:28Z

5

The built-in collections.Counter handles this elegantly:

>>> from collections import Counter
>>> mydata = [['apple', 'pear', 'apple'], ['apple', 'apple'], ['apple', 'pear', 'apple','apple', 'pear', 'apple']]
>>> Counter(map(len, mydata))
Counter({3: 1, 2: 1, 6: 1})
>>> Counter(len(sublist) for sublist in mydata) # or with a generator expression
Counter({3: 1, 2: 1, 6: 1})

answered May 2, 2020 at 17:44

Karl Knechtel

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Comments

Mark · Accepted Answer · 2020-05-02 19:01:09Z

4

You can pass the lengths to collections.Counter with something like:

from collections import Counter

l = [['apple', 'pear', 'apple'], ['apple', 'apple'],['apple', 'apple'],['apple', 'apple'], ['apple', 'pear', 'apple','apple', 'pear', 'apple'], ['apple', 'pear', 'apple']]

counts = Counter(map(len,l))

And get dictionary counts like:

Counter({3: 2, 2: 3, 6: 1})

There are 2 of length 3, 3 of length 2, and 1 of length 6.

You can access the counts like any dictionary:

>> counts[2]
3

edited May 2, 2020 at 19:01

answered May 2, 2020 at 17:44

Mark

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Comments

vish0709 · Accepted Answer · 2020-05-02 17:52:25Z

0

lst = [['apple', 'pear', 'apple'], ['apple', 'apple'], ['apple', 'pear', 'apple','apple', 'pear', 'apple'],['apple', 'apple']]
def countList(lst): 
    lst_dict = {}
    for i in lst:
        if len(i) not in lst_dict:
            lst_dict[len(i)] = 1
        else:
            lst_dict[len(i)] = lst_dict[len(i)]+1
    return lst_dict

print(countList(lst))

>> {3: 1, 2: 2, 6: 1}

Here keys are the length of the lists and values are the number of lists.

answered May 2, 2020 at 17:52

vish0709

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Comments

Abhishek Prusty · Accepted Answer · 2020-05-02 17:56:37Z

0

lst = [['apple', 'pear', 'apple'], ['apple', 'apple'], ['apple', 'pear', 'apple','apple', 'pear', 'apple'], ['mango', 'apple'], ['mango', 'mango']]

ctr_dict = {}

for i in lst:
    item_length = len(i)
    if str(item_length) in ctr_dict:
        ctr_dict[str(item_length)] = ctr_dict[str(item_length)] + 1
    else:
        ctr_dict[str(item_length)] = 1

for k,v in ctr_dict.items():
    print(k," strings:", v, "lists")

output: 
3  strings: 1 lists
2  strings: 3 lists
6  strings: 1 lists

answered May 2, 2020 at 17:56

Abhishek Prusty

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1 Comment

Abhishek Prusty Over a year ago

Happy to help, and welcome to Stack Overflow ! If this answer or any other one really solved your issue, please mark it as accepted.

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