Asked by Miguelcm90
on 9 Sep 2013

Dear Friends,

I would need to do the same as I asked in the question: "how to calculate differences inside an array , looping through a matrix and saving results" I do not want to repeat the question so as not to be repetitive.

I got this answer.

[a,b]=unique(x(:,1),'stable'); b=[b;size(x,1)]; out=nan(size(x)); for k=1:numel(b)-1 i1=b(k)+1; i2=b(k+1)-1; out(i1:i2,:)=bsxfun(@minus,x(i1:i2,:),x(i1-1,:)); end out(isnan(out(:,1)),:)=[]; out=out(:,2:end)

Taking into account the results provided in this wire, below are shown only a sample of them see original file in:

https://www.dropbox.com/s/kpifg9z43x4me39/out.txt

imput :

306 305,952 304,683 302,265 300,219 (1) 406 406,016 404,943 402,467 400,224 (2) 506 506,038 505,182 502,518 500,878 (3) 606 605,983 605,304 602,749 601,037 (4) 706 705,992 705,459 703,378 701,678 (5) 806 806,027 805,31 803,212 801,897 (6) 906 906,015 905,542 903,513 902,139 (7)->jump 306 306,008 304,977 302,45 299,846 (8)<- 406 406,009 404,961 402,483 400,361 (9) 506 506,003 505,208 502,728 500,684 (10) 606 605,999 605,447 603,032 601,458 (11) 706 706,012 705,41 703,335 702,125 (12) 806 806,02 805,462 803,338 801,901 (13) 906 906,014 905,25 903,571 901,725 (14)

desired output: this should be the first group:

100 100,064 100,26 100,202 100,005 (row2-row1) 200 200,086 200,499 200,253 200,659 (row3-row1) 300 300,031 300,621 300,484 300,818 (row4-row1) 400 400,04 400,776 401,113 401,459 (row5-row1) 500 500,075 500,627 500,947 501,678 (row6-row1) 600 600,063 600,859 601,248 601,92 (row7-row1)->jump 100 100,001 99,984 100,033 100,515 (row9-row8)-< 200 199,995 200,231 200,278 200,838 (row10-row8) 300 299,991 300,47 300,582 301,612 (row11-row8) 400 400,004 400,433 400,885 402,279 (row12-row8) 500 500,012 500,485 500,888 502,055 (row13-row8) 600 600,006 600,273 601,121 601,879 (row14-row8)

the calculations, start substracting from the second row the first one. then, the from the third to the first one. as you can see in the output. It is like absolute references in Excel, but, changing this reference to the smallest value of the first columm. This first columnn is not used in the calculations but I think is useful to index the arrays. having the start in the smallest value, and ending the loop in the biggest value found in the columm/array.It would be good if it can be applied for more columms and more rows. I do not know if It is possible. Any help is welcome. I think the code to write , is quite similar as one is shown here.

Thank you very much for your help. and I hope your reply.

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Answer by Andrei Bobrov
on 9 Sep 2013

Edited by Andrei Bobrov
on 9 Sep 2013

Accepted answer

m = dlmread('path_your_out.txt'); t=[true;diff(m(:,1)) < 0]; out = m-n(cumsum(t),:); out = out(any(out,2),:);

or

m = dlmread('path_your_out.txt'); s = size(m,2); n = find(diff(m(:,1))<0,1,'first'); m1 = reshape(m,n,[],s); m2 = bsxfun(@minus,m1(2:end,:,:),m1(1,:,:)); out = reshape(m2,[],s);

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