# How do I divide by the corresponding element in the list while using zip()

## How do I divide by the corresponding element in the list while using zip()

Contents

Problem Description:

I am trying to find out how can I do `(i1+i2)/[i]` for the ith element before getting the mean.

``````import numpy as np

def avg_prod(l1, l2):
np.mean([i1 * i2 for i1, i2 in zip(l1, l2)])
``````

I tried to use `i` inside the code, but it produces an error.

## Solution – 1

You can use `enumerate`:

``````def avg_prod(l1, l2):
np.mean([i1 * i2 / i for i, (i1, i2) in enumerate(zip(l1, l2))])
``````

or iterate over indices:

``````def avg_prod(l1, l2):
np.mean([l1[i] * l2[i] / i for i in range(min(len(l1), len(l2)))])
``````

you can minimize it in case you are sure that the lengths of the lists are equal:

``````def avg_prod(l1, l2):
np.mean([l1[i] * l2[i] / i for i in range(len(l1))])
``````
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