[scilab-Users] problem with creating loop

[Mike Page]

Hi Marcin,

You can find the unique elements of your first column using the unique
function like:

-->u=unique(xy_w(:,1))
 u  =

    1.
    4.
    6.

Then you can iterate over those values using:

-->for x=u'
-->av = mean(xy_w(find(xy_w(:,1)==x),2:3),'r')
-->end
 av  =

    21.    21.
 av  =

    44.    46.
 av  =

    35.    35.

Hope that helps.

Mike.


  -----Original Message-----
  From: marcin.wozniczka Gazeta.pl [mailto:marcin.wozniczka at gazeta.pl]
  Sent: 14 August 2010 18:05
  To: users at lists.scilab.org
  Subject: Re: [scilab-Users] problem with creating loop


  Ok I understand, but what can I do if the numbers in the first column are
not 1, 2, 3 etc., for example matrix a is looking like that:
  xy_w = [...
  6 10 10
  1 20 20
  4 40 40
  4 50 50
  6 60 60
  4 42 48
  1 22 22 ];


  I modified your function for that:
  nr = a(:,1);      //This is wrong
  for i=1:3        //This is wrong
    ps = nr(i);
    for j=1:3
      av(i,j) =mean(a(a(:,1) == ps,j));
    end
  end


  but I have problem to define final value of 'i'. I know that it's
conecting with 'nr' so if you know how I can declare only once the numbers
from first column (only numbers: 6, 1 & 4)


  --
  Marcin Woźniczka







    Hi Marcin,



    There are off course various ways to solve your problem. Probably the
shortest way to do is like this:



    for it=1:3;

       average(it) =mean(a(a(:,1)==it,2:$));

    end



    It loops over the elements in the first column. The second line is a bit
more cryptic but can be split in separate line:

    msk = a(:,1)==it;                                // creates a boolean
mask vector

    anew = a(msk,2:$);                          // creates a new matrix
using the mask over the second to last columns of a

    average=mean(anew);                  // calculate the average of the
matrix



    Cheers



    Francis









    From: marcin.wozniczka Gazeta.pl [mailto:marcin.wozniczka at gazeta.pl]
    Sent: 12 August 2010 20:59
    To: users at lists.scilab.org
    Subject: [scilab-Users] problem with creating loop



    Hello,

    I have small problem with my program/function in Scilab. I want to loop
function - the loop must be repeated until all datas will be use. For
example I have matrix 'a'

    a = [1 10 20

           2 20 30

           3 30 40

           1 20 10

           3 40 40
           2 20 10]

    and I'm taking all lines which have in the first column the same number,
take average of this and put to the other matrix. I created function which
can do all this thing but I don't have any idea how to make a reapeted loop
from this.



    Can you help me?


    --
    Marcin Woźniczka


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  --
  Pozdrawiam,
  Marcin Woźniczka
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