CODEWITHSUNDEEP
pythonpython-3.xnumpy
iNeedHelp
iNeedHelp

Reputation: 1

Numpy/Arrays Function

Write a function calc_frac(a,axis=0) that takes a 2-dimensional numpy array containing only zeros and ones and returns an array giving the fraction of ones in each column (if axis=0) or in each row (if axis=1).

This is what I have so far

import numpy as np
a = np.array([[1,0,1],[1,1,0],[0,1,0]])
b = np.zeros((3,1))
col_r1 = a[:,0:1]
col_r2 = a[:,1:2]
col_r3 = a[:,2:3]
i=0
j=0
k=0
for i in col_r1:
    if i >= 1:
        i = i+1
        b[0]= i/3

for k in col_r2:
    if k >= 1:
        k=k+1
        b[1] = k/3

for f in col_r3:
    if f >= 1:
        f=f+1
        b[2] = f/3
print(b)
print(col_r3)

Here are the problems I have:

  1. If you print b after all the mutations it shows b[2] as 0.6667 instead of 0.333. since the column should have only 1 copy of the number 1

  2. I'm not sure how I could rewrite this code as a function in the format shown above in the question.

  3. As I'm not familiar with numpy I was wondering if there was a way to write a code that does the same function without using for loops.

Thanks in advance

Upvotes: 0

Views: 167

Answers (1)

juanpa.arrivillaga
juanpa.arrivillaga

Reputation: 95873

def calc_frac(a, axis=0):
    return a.mean(axis=axis)

The key is that the mean of an array of ones and zeros is the fraction of 1's.

Upvotes: 1

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