Add total number of results in each call

[anitacaron]

Also, add the page number and the total number of pages.

[anitacaron]

Hi @pkalita-lbl, is there a way of having the total number of elements returned when returning an Iterable?

[pkalita-lbl]

There are a few different ways to get the length of an Iterable. I usually reach for the functools.reduce function:

import functools

iterable = ...
# starting with p = 0, compute p + 1 for each element
num_elements = functools.reduce(lambda prev, curr: prev + 1, iterable, 0)

Depending on exactly what type of Iterable you're dealing with it might be worth checking for a __len__ property:

def count(iterable):
    if hasattr(iterable, '__len__'):
        return len(iterable)
    return functools.reduce(lambda prev, curr: prev + 1, iterable, 0)

If you need to get the count without exhausting the original Iterable (for example, if you need to return the first N elements and the count), itertools.tee is useful:

import itertools
import functools

iterable = range(3000)
iter_1, iter_2 = itertools.tee(iterable)
result = {
    'items': list(itertools.islice(iter_1, 10)), 
    'total': functools.reduce(lambda prev, curr: prev + 1, iter_2, 0),
}
# --> {'items': [0, 1, 2, 3, 4, 5, 6, 7, 8, 9], 'total': 3000}

[anitacaron]

Thank you, @pkalita-lbl!! I'll try the tee function.