How to extract rows from a large number of rows that matchs a unique element in the column

eg

       ID             Test1         Test2        Test 3                                                                               
       1               10.1          100         100
       2               200           0.1         400
       3               50            80          20.123     
       4               1000          2000        3000
       5               0              1          10.987

say i have a column vector a = [ 20.123 10.987]' my desired result would be ans=

       3        50       80          20.123  

       5         0        1          10.987

I have a set of column vector a = (42x1)' and wish to filter through a large number of rows in a matrix to extract rows from specific column which matches with one element of my column vector. can we use logical indexing for this?

[madhan ravi]

A clear example edit your code properly so that it’s easy to read the datas

[Young Lee]

sorry I have fixed it now

[Walter Roberson]

I cannot tell what the relationship is between your column vector and anything else, and I do not see where the third column of your output comes from?

[madhan ravi]

@sir Walter the OP wants to find the common elements of a and matrix and want to extract the corresponding row from the matrix

[Walter Roberson]

Ah. When I was reading the question on my phone, I could not see the additional columns in the matrix.

[madhan ravi]

Ok sir Walter

Answer 1

[madhan ravi]

>> matrix =        [  1               10.1          100         100
                      2               200           0.1         400
                      3               50            80          20.123     
                      4               1000          2000        3000
                      5               0              1          10.987 ];
                  a = [ 20.123 10.987]
                  idx = ismember(matrix,a);

                  [idx1,~]= find(idx==1);
                  myreesult = matrix((idx1),:)

a =

     20.1230   10.9870

myresult =

      3.0000   50.0000   80.0000   20.1230
      5.0000         0    1.0000   10.9870

>>

[madhan ravi]

if you got your answer for the question accept the answer else let know what's additionally required

[Young Lee]

Thank you that worked perfectly,

[madhan ravi]

you're welcome :)

[Walter Roberson]

You should use ismembertol()