How to do matching in table format?

Hi,

I have some data, putting in a matrix A:-

    Col1 = [1;4;0];
    Col2 = [2;5;2];
    Col3 = [3;6;4];
    A = [Col1,Col2,Col3]

I want to extract the rows where column 2 have the value 2 (i.e. c), and also have another output with those values being updated from 2 to 200 (i.e. d).

    b=(A(:,2)==2);
    c=A(b,:)
    d=A;
    d(b,2)=200

However, now the data I obtained is a table, instead of a matrix:-

    A2 = table(Col1,Col2,Col3)

I tried to use A2 to replace A in the above codes and try to obtain c and d, but I failed.

How can I obtain c and d? Many thanks!

[dpb]

If the operations on the data are more convenient as array rather than as separate variables, then create the table variable as an array instead --

A2=table(A);

If there are specific reasons for keeping separate columns because most is column/variable related but there's the occasional array operation, you can retrieve the desired columns as array--

A2=table(Col1,Col2,Col3);
a=A{:,1:3};

and a is the array equivalent to A above to operate on and then put result back into the table.

Answer 1

[Peter Perkins]

    b = (A2.col2 == 2); % or A2{:,2) == 2
    c = A(b,:) % leave this as a table
    d = A2;
    d.Col2(b) = 200; % or d{b,2} = 200

There's quite a lot of documentation about table subscripting that will explain all this.