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

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?

Answer 1

[ANKUR KUMAR]

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))

[Rusty Rudolph]

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.

[ANKUR KUMAR]

"(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.

[ANKUR KUMAR]

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'