How can I extract only the information about the same group from the table information?

Currently, I would like to extract only the information about the same group of tables.

For example, in a table named A

1 3 2 
1 4 5 
1 5 6
1 6 8
2 3 7
2 5 3 
2 7 4
3 9 6
3 4 2

I want to extract the information about the group [1,2,3] for the first column.

[dpb]

See

doc ismember

[Maadhav Akula]

Hi @shoki kobayashi,

Can you be more specific what information you want to extract? If it's just whether the Group [1,2,3] are present in the first column of A, then as @dpb mentioned ismember function would help you out.

[dpb]

Actually, rereading the Q? and looking at the data more closely, I'm guessing what OP is looking for is grouping variables.

Depending upon just what is meant by "table" here, rowfun, varfun or findgroups, splitapply are likely what is really wanted/need.

[shoki kobayashi]

Thanks for the reply, @dpb and @Maadhav Akula.

Using ismember worked for me.

I'm sorry that my question was misinterpreted.