Split a list with a adjustable ratio


so i am trying to create a function that split a list with values with an adjustable ratio.

To just split the list in half i have this function:

def list_splitter(list_to_split):  

    half = len(list_to_split) // 2
    return list_to_split[:half], list_to_split[half:]

Where list_to_split has 1000 objects. But i want to do something like this:

def list_splitter(list_to_split, ratio):

    part1 = len(list_to_split) * ratio
    part2 = 1 - ratio 
    return list_to_split[:part1], list_to_split[part2:]

So for example i want to be able to set ratio = 0.75, so that 0.75% (750 objects) is added in the first part, and 250 in the other part.

Asked By: Jappe



Well, something like this should do it:

def list_splitter(list_to_split, ratio):
    elements = len(list_to_split)
    middle = int(elements * ratio)
    return [list_to_split[:middle], list_to_split[middle:]]
Answered By: zipa

You can do like this:
If your ratio will change every time, then:

def list_splitter(list_to_split, ratio):
    first_half = int(len(list_to_split) * ratio)
    return list_to_split[:first_half], list_to_split[first_half:]
Answered By: ATS

A one-liner using numpy

import numpy as np 

l = np.random.rand(1000)
ratio = 0.75

y = np.split(l, [round(len(l) * ratio), len(l)])

print(len(y[0]), len(y[1]))
Answered By: Mikel B
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