For-Loop Alternative for Faster Code Execution
6 views (last 30 days)
Show older comments
Suppose,
a{1}=[1 6;
1 9;
1 8;
3 7;
3 0;
4 0;
5 0;
5 0;
5 0;
5 0;]
desired_answer{1}= [1 6;
1 6;
1 6;
3 9;
3 9;
4 8;
5 7;
5 7;
5 7;
5 7;]
Is there a more efficient way I can do this without having to use for loop? (Cell Array is used because it is adapted from my problem)
2 Comments
Matthew Eicholtz
on 27 Jun 2013
Can you provide more details? Here is what I conclude from your description: the number of nonzero entries in the second column equals the number of unique values in the first column; then, you want to assign each of the second-column values to all instances of the appropriate first-column value, in order. Is that correct?
Accepted Answer
Matthew Eicholtz
on 27 Jun 2013
Still unsure about your problem setup, but the following code will yield your desired result for the example above.
[~,~,idx] = unique(a{1}(:,1));
a{1}(:,2) = a{1}(idx,2);
0 Comments
More Answers (1)
Matthew Eicholtz
on 27 Jun 2013
And if the for loop you are concerned about is looping through the cells in your cell array, then try this code:
[~,~,idx] = cellfun(@(x) unique(x(:,1)),a,'uni',0);
a = cellfun(@(x,y) [x(:,1) y],a,cellfun(@(z,i) z(i,2) ,a,idx,'uni',0),'uni',0);
Perhaps this is not the most elegant solution, in which case I expect the MATLAB pros will chime in shortly.
0 Comments
See Also
Categories
Find more on Loops and Conditional Statements in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!