How to If certain number is in one column, record another number in another column

Hello,

I am very new to matlab and trying to learn how to code my project, any help would be much appreciated.

Currently, I am trying to code a script that if there is one number already avaliable at one column, it would put the other number in the other column. For example, I am trying to get number 0, 1 randomly coded in to column 2 and 3. If there is a 0 on column 2, I would like to have 1 on column 3 and vice versa. So it would look something like this.

A = [ 1  0  1   
      2  1  0  
      3  1  0  
      4  0  1 ]

I managed to get the 0 and 1 randomly distrbuted on column 2, but I am having trouble with putting the numbers in for column 3.

Would anyone know an effiecnt way to do it?

Below is the code that I was trying to use.

Datafile(:,2) = mod(reshape(randperm(96*1), 96, 1), 2) %the 96 is there becuase I just have 96 rows
Datafile(96:3) =0 
    if Datafile(:,2) == 0
       Datafile(:,4) = 1
    end

Many thanks!

Answer 1

[Voss]

If the value in the second column is x, then the value of the fourth column should be 1-x. This is true because 1-0=1 and 1-1=0. (If you need to do a similar thing with numbers other than 0 and 1, a similar linear transform can be found: if column 2 is x, an element from {a,b}, then column 4 is (a+b)-x. thus, a->b and b->a.)

Datafile(:,2) = mod(reshape(randperm(96*1), 96, 1), 2);
% Datafile(96:3) =0; % btw, this line has no effect because 96:3 is an empty array
% Datafile(:,3) = 0; % do this to initialize the third column to all zeros, but even this is unnecessary because
Datafile(:,4) = 1-Datafile(:,2); % this line will put the fourth column in place (filling in the third with zeros if it's not there aleady)

[Sojung Youn]

This is amazing! Thank you so much for the comments as well!