How can I change one column of a .mat file ?

I have a .mat file which is a 1769x97 matrix of numbers. The 97th column is composed of numbers going from 1 to 100 and I need to change them to numbers going from 1 to 4. There are 1769 values (around 18 for each number of the 100) so I can't do it by hand. I need to change the values between 1 and 5, 11 and 15, 21 and 25... to 1, the values between 6 and 10, 16 and 20... to 2, the values between 51 and 55, 61 and 65... to 3 and the values between 56 and 60, 66, and 70... to 4.

What I thought of doing was this:

      load matrix1769x97.mat %this creates my matrix called A in the workspace.

      for i=1:1769
              if A(i,97)== 1:5 || 11:15 || 21:25 || 31:35 || 41:45
                 A(i,97)== 1
              end
              if A(i,97)== 6:10 || 16:20 || 26:30 || 36:40 || 46:50
                 A(i,97)== 2 
              end
              if A(i,97)== 51:55 || 61:65 || 71:75 || 81:85 || 91:95
                 A(i,97)== 3 
              end
              if A(i,97)== 56:60 || 66:70 || 76:80 || 86:90 || 96:100
                 A(i,97)==4 
              end
      end

It doesn't work. What changes would you do to the code? And also, can I save the new A to another .mat file after doing this? How can I do it?

Thanks in advance! :-)

Answer 1

[Takuji Fukumoto]

I think you need to write conditional statement like here

if A(i,97)== 1:5 || A(i,97)== 11:15 || A(i,97)== || 21:25 ...

I simpify the structure. you can do that with this code.

        for i=1:1769
                if A(i,97)  <= 50
                    if mod(A(i,97),10) <= 5 && mod(A(i,97),10) ~= 0
                        A(i,97)= 1;
                    else
                        A(i,97)= 2;
                    end
                else
                    if mod(A(i,97),10) <= 5 && mod(A(i,97),10) ~= 0
                        A(i,97)= 3;
                    else
                        A(i,97)= 4;
                    end
                end
        end

[Pablo Heredia]

Thank you Takeru! Problem solved

Answer 2

[Takuji Fukumoto]

You can replace data in a colum. Please see below.

imax1 = 100
imax2=4;
data = randi(imax1,[1769,97]);
newcol = randi(imax2,[1769,1]);
data(:,end) = newcol;

[Pablo Heredia]

Thank you for the answer Takeru. However, it doesn't solve my problem. I realised my question wasn't complete, so I have specified a little bit more what I need to do.