Speed issues with python

Question

I'm struggling with speeding up my python code. I think that the main bottleneck of my code is located in the following function, where k is a counter, m is an empty matrix and image3 is a matrix that contains 0s and 1s. Do you have any suggestion? p.s I have already try to use Cython without much success, so I was wondering if there are some simpler way of solving the problem. Thank you in advance for help.

 def make_step(k,m,image3): for i in range(len(m)): for j in range(len(m[i])): if m[i][j] == k: if i>0 and m[i-1][j] == 0 and image3[i-1][j] == 0: m[i-1][j] = k + 1 if j>0 and m[i][j-1] == 0 and image3[i][j-1] == 0: m[i][j-1] = k + 1 if i<len(m)-1 and m[i+1][j] == 0 and image3[i+1][j] == 0: m[i+1][j] = k + 1 if j<len(m[i])-1 and m[i][j+1] == 0 and image3[i][j+1] == 0: m[i][j+1] = k + 1

I’m voting to close this question because your code works but you are looking for a code review. Thus this question belongs on: codereview.stackexchange.com — Booboo
– Booboo, Commented Mar 10, 2021 at 11:53
could you share the full example of how you change k variable outside of this function? — Singlet
– Singlet, Commented Mar 10, 2021 at 13:36
also, you say m is empty but do you mean it is initially a matrix of zeroes? And then progressively updated as k is increased? — Stuart
– Stuart, Commented Mar 10, 2021 at 21:08

Glauco · Accepted Answer · 2021-03-11 09:59:51Z

I agree with Booboo, your code need review, and i suggest following approach:

Do a good benchmark to see where the time is spent. For these kind of problem perf_tool is a valid tool designed for this[*]. After you know where the code lack, you can rewrite the internal loop in vectorial using mask approach. This let you to reduce problem from O(n*m) to O(n)

[*] I'm the main developer of perf_tool

Collectives™ on Stack Overflow

Speed issues with python

1 Answer 1

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Linked

Related