size of a whole list containing tuple

Question

I have a list made of tuple

liste_groupe=((image1, image2, image6),(image5, image4, image8, image7, image3, image9))

and i would like to have the number of element of all the tuple ie here the result would be 9

I have tried len(liste_groupe) but it gives me 2.

So what code should I write in order to have the number of all the element of all the tuples in a list ?

The number of elements regardless of containment level direct in outer sequence or inner (nested) sequence I understand. One solution is flattening and counting the result like described at http://stackoverflow.com/questions/5828123/nested-list-and-count and several other places ;-) — Dilettant, Jun 02 '16 at 16:50

score 2 · Accepted Answer · answered Jun 02 '16 at 16:52

2

There is no need to flatten the list in order to find the total length, and there is no need to use recursion if you already know the list is a simple 2D structure. This is all you need:

sum(map(len, liste_groupe))

answered Jun 02 '16 at 16:52

Alex Hall

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SparkAndShine · Answer 2 · 2016-06-02T17:00:48.917

1

Flatten a tuple of tuples into a list,

>>> liste_groupe=(('image1', 'image2', 'image6'),('image5', 'image4', 'image8', 'image7', 'image3', 'image9'))
>>> l = [item for t in liste_groupe for item in t]
>>> len(l)
9

# Or use itertools.chain
>>> import itertools
>>> l = list(itertools.chain(*liste_groupe))
>>> len(l)
9

If you only care about the number of elements,

>>> count = sum([len(t) for t in liste_groupe])
>>> count
9

edited Jun 02 '16 at 17:00

answered Jun 02 '16 at 16:49

SparkAndShine

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1

Why actually flatten the list if you just want to calculate the length? Seems wasteful. – Alex Hall Jun 02 '16 at 16:55
@AlexHall, you're right. Your answer is great, should be accepted. – SparkAndShine Jun 02 '16 at 17:08

score 0 · Answer 3 · answered Jun 02 '16 at 16:51

You can follow a recursive approach:

def tuple_length( t ):
    if type(t) != tuple:
        return 1
    length = 0
    for element in t:
        length += tuple_length( element )
    return length

Now, tuple_length(liste_groupe) will return 9 as expected.

score 0 · Answer 4 · answered Jun 02 '16 at 16:51

Recursion could accomplish this for you. With the following function the size of an n-dimensional tuple or list could be counted.

def calculate_size(data_set, size=0):
    for i in data_set:
        if isinstance(i, tuple) or isinstance(i, list):
            size += calculate_size(i)
        else:
            size += 1
    return size

score 0 · Answer 5 · answered Jun 02 '16 at 16:53

0

Will work for a single nested list. For deeper or irregularly nested lists, you'll need a recursive function that uses chain.

from itertools import chain

cnt = len(list(chain.from_iterable(list_group)))

answered Jun 02 '16 at 16:53

Brendan Abel

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size of a whole list containing tuple

5 Answers5