Python increment part of an array

Question

I would like to increment part of an array in python as fast as possible. I use a simple loop :

>>> test = [0,0,0,0,0]
>>> for i in xrange(1, 3):
    test[i] += 1

>>> test
[0,1,1,0,0]

In my program the test list contains several millions elements. Maybe numpy could be the solution ?

Thanks,

Marc

John Zwinck · Accepted Answer · 2014-10-17 06:57:13Z

3

NumPy is indeed a solution:

import numpy as np
arr = np.array(test)
arr[1:3] += 1

You can use arr.tolist() if you really need to go back to a list but better would be to use a NumPy array right from the start, wherever you get your data.

answered Oct 17, 2014 at 6:57

John Zwinck

252k44 gold badges346 silver badges459 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

John Zwinck Over a year ago

@MarcMonot: thank you, perhaps you could upvote to offset the beautiful snowflake that downvoted this, and accept it if your problem is resolved by this. Welcome to Stack Overflow.

Marc Monot Over a year ago

I already tried by I can't up vote for that I need 15 reputations :)

Marc Monot Over a year ago

Ah ok, I marked the answer and earn reputation, then I vote up :) Thanks again.

Collectives™ on Stack Overflow

Python increment part of an array

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related