Remove array values with multiple occurances from "parent" array
1 view (last 30 days)
Show older comments
How do you remove values in an array from a "master database" array? For example:
a = [1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4]
b = [1, 1, 2, 4, 4, 4]
I would like to remove each occurance of each value in 'b' from 'a' to get:
c = 1, 2, 2, 3, 3, 3
setdiff(a, b) doesn't work because it removes all instances from 'a' including the repeating values (it even says no repetitions in the documentation):
c = 3
[~, col] = ismember(b, a)
a(col) = []
doesn't work because it only removes one instance of the numbers (the first index where it occured):
c = 1, 1, 2, 2, 3, 3, 3, 4, 4
Thanks for the help.
0 Comments
Accepted Answer
David Hill
on 9 Jul 2020
Edited: David Hill
on 9 Jul 2020
a = [1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4];
b = [1, 1, 2, 4, 4, 4];
c = a;
for i=b
c(find(c==i,1))=[];
end
More Answers (1)
Bruno Luong
on 10 Jul 2020
Edited: Bruno Luong
on 10 Jul 2020
Test samples
a = [1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4]
b = [1, 1, 2, 4, 4, 4]
Code
u = unique([a,b]);
n = length(u);
[~, ia] = ismember(a,u); na = accumarray(ia(:),1,[n 1]);
[~, ib] = ismember(b,u); nb = accumarray(ib(:),1,[n 1]);
c = repelem(u,max(na-nb,0))
Result
c =
1 2 2 3 3 3
0 Comments
See Also
Categories
Find more on Multidimensional Arrays 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!