Logical indexing in tables with multiple targets

Suppose you have a table such as the one below:

Sample = [0;1;1;2;2;2];
Data = [rand(1,5);rand(1,5);rand(1,5);rand(1,5);rand(1,5);rand(1,5)];
A = table(Sample,Data)

A = 6×2 table
    Sample                                Data                            
    ______    ____________________________________________________________

      0        0.21426      0.64868      0.07936      0.58883      0.75634
      1        0.36764      0.46345      0.56078      0.12871      0.19823
      1        0.58486      0.18506     0.029363      0.31866       0.2336
      2        0.53846      0.47363      0.99926      0.29129      0.61109
      2       0.063376      0.99878      0.36276       0.1082    0.0017856
      2        0.89091      0.85546     0.011542      0.98834      0.88992

Now say you want to extract only a subset a data that corresponds to certain Sample numbers. I know of a coup[le ways to do this.

You can do row-wise deletion if your table isn't too large and you know the row numbers of what you want to delete. Or you can just call the rows that you care about and assign it to a new table.

B = A;
B(1:3,:) =[]; %This deletes the Samples 0 and 1, but leaves 2.
B

B = 3×2 table
    Sample                                Data                            
    ______    ____________________________________________________________

      2        0.53846      0.47363      0.99926      0.29129      0.61109
      2       0.063376      0.99878      0.36276       0.1082    0.0017856
      2        0.89091      0.85546     0.011542      0.98834      0.88992

B = A;
B = B(4:6,:)

B = 3×2 table
    Sample                                Data                            
    ______    ____________________________________________________________

      2        0.53846      0.47363      0.99926      0.29129      0.61109
      2       0.063376      0.99878      0.36276       0.1082    0.0017856
      2        0.89091      0.85546     0.011542      0.98834      0.88992

But if your table is large, I prefer to use some logical indexing:

B = A;
B = A(A.Sample == 2,:)

B = 3×2 table
    Sample                                Data                            
    ______    ____________________________________________________________

      2        0.53846      0.47363      0.99926      0.29129      0.61109
      2       0.063376      0.99878      0.36276       0.1082    0.0017856
      2        0.89091      0.85546     0.011542      0.98834      0.88992

Now what if I want to have multiple targets in the mask of my logical lindex. I know I can combine multiple logical indicies (indexes?) as below, but then how do I pass that along to the table?

B = A;
C = A.Sample == 0;
D = A.Sample == 2;
E = C|D

E = 6×1 logical array
   1
   0
   0
   1
   1
   1

B = B(B.Sample(E),:)

Error using ()
Index in position 1 is invalid. Array indices must be positive integers or logical values.

Really, I am hoping there is a way to make the following workflow happen without going through for loops for each target of my logical index, but I might have to homebrew my own function to accomplish this.

C = [1,5,23]; % An array of the Sample numbers I'd like to keep in my new table

B = A(A.Sample == C,:); 

If anyone knows a better way to do this so I can avoind clunky blocks in my script that will piecewise pull out the bits that I need, I would really appreciate it. Thanks in advance!

Answer 1

[Bruno Luong]

Note that what I wrote here is very similar to standard array.

Sample = [0;1;1;2;2;2];
Data = [rand(1,5);rand(1,5);rand(1,5);rand(1,5);rand(1,5);rand(1,5)];
A = table(Sample,Data)

A = 6×2 table
    Sample                              Data                          
    ______    ________________________________________________________

      0        0.51977     0.58779      0.9266     0.98092     0.28373
      1        0.67344     0.67279     0.28825    0.015219     0.20328
      1       0.051701     0.58111     0.43058     0.11597     0.78534
      2        0.65281     0.99898     0.51989     0.75293     0.99619
      2        0.44047     0.91429     0.78285     0.83373     0.61386
      2        0.26829     0.64501     0.28681     0.32614     0.93582

B = A;
C = A.Sample == 0;
D = A.Sample == 2;
E = C|D

E = 6×1 logical array
   1
   0
   0
   1
   1
   1

B = B(E,:) % Fix your error

B = 4×2 table
    Sample                           Data                        
    ______    ___________________________________________________

      0       0.51977    0.58779     0.9266    0.98092    0.28373
      2       0.65281    0.99898    0.51989    0.75293    0.99619
      2       0.44047    0.91429    0.78285    0.83373    0.61386
      2       0.26829    0.64501    0.28681    0.32614    0.93582

C = [1,5,23]; % An array of the Sample numbers I'd like to keep in my new table
B = A(ismember(A.Sample,C),:) % This will meet your last wish

B = 2×2 table
    Sample                              Data                          
    ______    ________________________________________________________

      1        0.67344     0.67279     0.28825    0.015219     0.20328
      1       0.051701     0.58111     0.43058     0.11597     0.78534

[ASM]

Thank you! I can't believe I was blind to that small detail. I appreciate your fast response.