How to split a matrix for different plots?

I have a matrix which the first column are 1 or 2 or 3 or 4 or 5 . I want to done a function and plot of datas in all rows which have in the first column same numbers. For example I habe a matrix like [ 1 23 240;2 22 100;2 44 900;1 33 800,... ]. Now I want plot a function to 1. and 4. row (f(23)& f(33))in red color and the 2. &3. row (f(22) & f (44)) with blue color. is there any solution with out loops?

Answer 1

[Stephan]

Hi,

for your matrix A:

>> A = [ 1 23 240;2 22 100;2 44 900;1 33 800]

A =

       1    23   240
       2    22   100
       2    44   900
       1    33   800

to get the data splitted without for loop use:

>> A1 = [A(A(:,1)==1,2),A(A(:,1)==1,3)]

A1 =

      23   240
      33   800

>> A2 = [A(A(:,1)==2,2),A(A(:,1)==2,3)]

A2 =

      22   100
      44   900

Now you have splitted data which you can plot however you want:

>> plot(A1(:,1),A1(:,2),'r')
>> hold on
>> plot(A2(:,1),A2(:,2),'b')

which gives:

Best regards

Stephan