How to add n elements in a list, where n is each item in another list?

Question

I have the following three lists:

numlist = [0,4,0,4,0,4,0,0,4,0,4]
upperlist = ['EF','FA','FE','FY','IF','OF']
lenwords = [2,2,2,2,2,2]

Where each item in lenwords represents the number of characters for each word in upperlist.

I want to add consecutive numbers in numlist n times, where n is equal to n in lenwords, so that the resulting list would look like this:

sumlist = [4,4,4,4,4,4]

The objective is to the zip upperlist and sumlist into a list of tuples, which would look something like this:

ziplist = [(4,'EF'), (4,'FA'), (4,'FE'), (4,'FY'), (4,'IF'), (4,'OF')]

I know how to zip both lists, I’m just getting stuck in how to access n in lenwords to add i + i+1 in numlist.

Asked By: Juliana Gómez

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Source

Answer 1

Use a variable to keep track of your progress

numlist = [0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4]
upperlist = ['EF', 'FA', 'FE', 'FY', 'IF', 'OF']
lenwords = [2, 2, 2, 2, 2, 2]

values = []
count = 0
for n in lenwords:
    values.append(sum(numlist[count:count + n]))
    count += n
print(values)
# [4, 4, 4, 4, 4, 4]

result = list(zip(values, upperlist))
print(result)
# [(4, 'EF'), (4, 'FA'), (4, 'FE'), (4, 'FY'), (4, 'IF'), (4, 'OF')]

Answered By: azro

Answer 2

With numpy:

import numpy as np

numlist = [0,4,0,4,0,4,0,4,0,4,0,4]
upperlist = ['EF','FA','FE','FY','IF','OF']
lenwords = [2,2,2,2,2,2]

x = np.r_[0, lenwords[:-1]].cumsum()
list(zip(np.add.reduceat(numlist, x), upperlist))

It gives:

[(4, 'EF'), (4, 'FA'), (4, 'FE'), (4, 'FY'), (4, 'IF'), (4, 'OF')]

Answered By: bb1

Answer 3

You can map over the lenwords and generate the consecutive sum.

numlist = [0, 4, 0, 4, 0, 4, 0, 0, 4, 0, 4]
upperlist = ['EF', 'FA', 'FE', 'FY', 'IF', 'OF']
lenwords = [2, 2, 2, 2, 2, 2]


def consecutiveSum(data):
    [index, n] = data
    return sum(numlist[index:index+n])


sumList = map(consecutiveSum, enumerate(lenwords))

print(sumList)  # [4, 4, 4, 4, 4, 4]

Answered By: Sifat Haque

How to add n elements in a list, where n is each item in another list?

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