Finding the average of every nth row but n is not fixed.
1 view (last 30 days)
Show older comments
Hello,
Consider a nx2 matrix M with
M= [
1 10
1 11
1 20
2 4
2 9
2 8
2 7
.
.
.
];
How to find the average of the second column when the first column change values, i.e. "1 rows" have 3
values while "2 rows" have 4, etc. so we need the average of the 3 first values, then the next four, etc.
Thank you.
Accepted Answer
Stephen23
on 23 Jul 2019
Edited: Stephen23
on 23 Jul 2019
>> M = [1,10;1,11;1,20;2,4;2,9;2,8;2,8];
>> V = accumarray(M(:,1),M(:,2),[],@mean)
V =
13.667
7.25
>> V = splitapply(@mean,M(:,2),M(:,1))
V =
13.667
7.25
And if you want those values back in the matrix:
>> M(:,3) = V(M(:,1))
M =
1 10 13.667
1 11 13.667
1 20 13.667
2 4 7.25
2 9 7.25
2 8 7.25
2 8 7.25
2 Comments
More Answers (0)
See Also
Categories
Find more on Logical 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!