RE: deleting duplicities, diag, equidistant data

[Hall, Benjamin]

Have you tried interp1 for creating equidistant samples from non-equidistant
ones?

-----Original Message-----
From: Jiri Pachman [mailto:address@hidden
Sent: Monday, February 28, 2005 3:03 AM
To: octave list
Subject: deleting duplicities, diag, equidistant data


thanks to all for answers to my previous questions

Hi everybody,
I have this simple problem. During data manipulation I create two  
(sometimes 3) columns of data. First contains x values the others are y,  
y2 values. It sometimes happens that I get two values of y are for the  
same value of x (around 5 couples in matrix of 200 lines). This makes  
problems in further calculations. I tried gnuplot´s smoothing (smooth  
spline) function and it works well, taking the duplicate values and making  
y average for particular x. Unfortunately I do not know, how to extract  
this data in numeric format from gnuplot. I was looking for something  
similar in octave, but without luck. Is there something like this in  
octave?

For now I am using the following script that finds the duplicate values  
and deletes them, but I would prefer to average them. I also tried to work  
with diagonal using matlabs diag function, but it seems to work quite  
differently (that is why I use rather complicated way to change 1 on the  
diagonal to 0).

x = G12;
vel = rows(x);
indexy = zeros(vel);
for i = 1:vel
ind = x(:,1) == x(i,1);
indexy(:,i) = ind;
diamat(i,i) = 1;
endfor

#% -------- indexes of duplicate values -------------
err = (indexy - diamat);
max(err)

#%--------------------- adding err columns creating index  ---------
ind = err(:,1);
for k=1:vel-1
ind = ind + err(:,k+1);
G12_nove = x(~ind, :);
endfor

I am also interested, if there is some elegant way how to create  
equidistant data from nonequidistant data. I use polynomial fit and then I  
calculate the new values in linspace or logspace depending on the need.

thanks for help

Jiri


-- 
***************************************************
Ing. Jiri Pachman
Katedra teorie a technologie vybusnin
Univerzita Pardubice
Studentska 95
532 10 Pardubice

tel.:  +420-46-603-8018
fax.: +420-46-603-8024
***************************************************



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