MATLAB Answers

0

How do i filter out certain values in a cell matrix using conditions for strings ?

Asked by Rusty Rudolph on 10 Oct 2018
Latest activity Commented on by ANKUR KUMAR on 10 Oct 2018
I have a cell matrix-
x = { 1 2 'a' 'q' ; 2 3 'a' 'p'; 3 4 'a' 'q'; 5 6 'b' 'p' ; 7 8 'b' 'q' ;9 8 'b' 'q';};
or x =
1 2 a q
2 3 a p
3 4 a q
5 6 b p
7 8 b q
9 8 b q
I want to filter out all rows that have 'a' in the 3rd column and 'q' in the fourth. My result matrix should be-
result=
1 2 a q
3 4 a q
How do I do this?

  0 Comments

Sign in to comment.

Products


Release

R2017a

1 Answer

Answer by ANKUR KUMAR on 10 Oct 2018
Edited by ANKUR KUMAR on 10 Oct 2018
 Accepted Answer

You can use contains to find the required letter. contains gives true if the part of search string contains in the main string.
x(contains(x(:,3),'a') & contains(x(:,4),'q'),(3:4))
Better to use strcmp, as it check for complete string. strcmp checks for the complete strings. It gives true only when the complete string is present.
x(strcmp(x(:,3),'a') & strcmp(x(:,4),'q'),(3:4))

  3 Comments

What if my strings were present in say 3rd and 6th columns, then how would I use strcmp? I don't understand the usage of " ,(3:4) " at the end in the expression you gave.
"(3:4) " is used because you wish to extract 3rd and fourth column as output. If you wish all, then use
x(strcmp(x(:,3),'a') & strcmp(x(:,4),'q'),:)
ans =
2×4 cell array
[1] [2] 'a' 'q'
[3] [4] 'a' 'q'
If data is on 3rd and 6th column, then use
x(strcmp(x(:,3),'a') & strcmp(x(:,6),'q'),:)
The above one gives output for complete columns.
For more clarification, refer this,
x = { 1 2 'a' 6 8 'q' ; 2 3 'a' 2 5 'p'; 3 4 'a' 2 1 'q'; 5 6 'b' 1 2 'p' ; 7 8 'b' 1 1 'q' ;9 8 'b' 1 1 'q';}
x =
6×6 cell array
[1] [2] 'a' [6] [8] 'q'
[2] [3] 'a' [2] [5] 'p'
[3] [4] 'a' [2] [1] 'q'
[5] [6] 'b' [1] [2] 'p'
[7] [8] 'b' [1] [1] 'q'
[9] [8] 'b' [1] [1] 'q'
1)
x(strcmp(x(:,3),'a') & strcmp(x(:,6),'q'),:)
ans =
2×6 cell array
[1] [2] 'a' [6] [8] 'q'
[3] [4] 'a' [2] [1] 'q'
2)
x(strcmp(x(:,3),'a') & strcmp(x(:,6),'q'),[3,6])
ans =
2×2 cell array
'a' 'q'
'a' 'q'

Sign in to comment.