Find common data between two vectors
4 views (last 30 days)
Show older comments
I have two vectors A and B they both are different length, but a good portion of the values are common to both.
A = [3 4 6 1 7 2 5 6 7 9 0 3 2 8];
B = [4 5 6 6 1 7 2 5 6 7 9 0 3 2 0 5 8 7];
I need to find the indices where [6 1 7 2 5 6 7 9 0 3 2] begin and end
ia = [3 13];
ib = [4 14]
2 Comments
Walter Roberson
on 12 Apr 2018
Are you looking for the beginning and ending indices of the largest consecutive common sequence ?
Accepted Answer
John D'Errico
on 12 Apr 2018
Edited: John D'Errico
on 12 Apr 2018
If you are looking for the longest common substring?
Assuming the elements of A and B are integers, then use of my commonsubstring utility works:
A = [3 4 6 1 7 2 5 6 7 9 0 3 2 8];
B = [4 5 6 6 1 7 2 5 6 7 9 0 3 2 0 5 8 7];
[S,ind1,ind2] = commonsubstring(char(A),char(B))
S =
' '
ind1 =
1×1 cell array
{[3]}
ind2 =
1×1 cell array
{[4]}
+S
ans =
6 1 7 2 5 6 7 9 0 3 2
So the common substring begins at element 3 of A, element 4 of B.
The length of the string is
numel(S)
ans =
11
So that gives you the end points in each string.
A = randi(9,1,10000);
B = randi(9,1,2000);
[S,ind1,ind2] = commonsubstring(char(A),char(B))
S =
' '
ind1 =
1×1 cell array
{[691]}
ind2 =
1×1 cell array
{[756]}
+S
ans =
5 4 4 2 3 1 9 6
It can be found here:
https://www.mathworks.com/matlabcentral/fileexchange/27460-string-subsequence-tools
More Answers (2)
Birdman
on 12 Apr 2018
One approach:
A = [3 4 6 1 7 2 5 6 7 9 0 3 2 8];
B = [4 5 6 6 1 7 2 5 6 7 9 0 3 2 0 5 8 7];
pattern = [6 1 7 2 5 6 7 9 0 3 2];
[ia1,ia2]=regexp(reshape(char(string(A)),1,[]),reshape(char(string(pattern)),1,[]));
[ib1,ib2]=regexp(reshape(char(string(B)),1,[]),reshape(char(string(pattern)),1,[]));
ia=[ia1 ia2]
ib=[ib1 ib2]
See Also
Categories
Find more on Characters and Strings 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!