MATLAB: If column a=[1;2;3;2;5;2], b=[1;2;3;4;5;6] how many rows have a==2, i use this [a]=find(a==2) .

Question

My question is on that a==2 row what is the value of row of column b.

Answer 1

a=[1;2;3;2;5;2];
b=[1;2;3;4;5;6];
how_many_rows_have_2_in_a = nnz(a==2)
corresponding_b_value_when_a_is_2 = b(a==2)

Gives:

how_many_rows_have_2_in_a =
     3
corresponding_b_value_when_a_is_2 =
     2
     4
     6     

If you still want to use find then:

how_many_rows_have_2_in_a = numel(find(a==2))
corresponding_b_value_when_a_is_2 = b(find(a==2))

Gives:

how_many_rows_have_2_in_a =
     3
     
corresponding_b_value_when_a_is_2 =
     2
     4
     6     

Note : Logical indexing is efficient than find.