how can i add 1-40,41-80, 81-120 and so on till 14000 datapoints which is in a text file?

sir....i have a text file which consist of 14000 rows and 2 columns.... i have to add the 40 points each till 14000 data... means 1-40 , 41-80, 81-120 and so on... what should i do for that???

Answer 1

[Walter Roberson]

You have two columns, so

squeeze( sum( reshape(YourData, 40, [], 2) ) )

[Ruby]

clc;
clear all;
close all; 
fid = fopen('file name.txt');
datacell = textscan(fid,'%f%f%f%*[^\n]',...
'delimiter','\t');
fclose(fid); 
A = datacell{2}; 
B=datacell{3};
C=A-B;

sir... with this code i can read the datas from a text file.... reshape is not working to sum up the 1st 40 datapoints.... based upon this code what changes i have to make??

[Ruby]

error in squeeze( sum( reshape(YourData, 40, [], 2) ) )... i can't clear the error...

[Walter Roberson]

The YourData that I used should be two column, as my assumption was that you wanted to do this addition as one step rather than one column at a time.

[Ruby]

Sir , this is the error shown.... pls give a suggetion

Error using reshape Product of known dimensions, 80, not divisible into total number of elements, 3.

[Image Analyst]

This works just fine for me:

YourData = rand(14000, 2); % Create random sample data 14,000 rows, 2 cols
squeeze( sum( reshape(YourData, 40, [], 2) ) )

What does it say when you do

whos YourData

[Ruby]

clc;
clear all;
close all; 
fid = fopen('filename.txt');
datacell= textscan(fid,'%f%f%f%*[^\n]',...
'delimiter','\t');
fclose(fid);
A = datacell{2}; 
B=datacell{3};
C=A-B;
datacell=rand(14000,2);
squeeze( sum( reshape(datacell, 40, [], 2) ) );

by using this error comes like..

Error using reshape
Product of known dimensions, 80, not divisible into total number of elements, 3.

[Ruby]

   fid = fopen('filename.txt');
  datacell= textscan(fid,'%f%f%f%*[^\n]',...
  'delimiter','\t');
  fclose(fid);
  A = datacell{2}; 
  B=datacell{3};
  C=A-B;
  t=0.0005:0.0005:0.065;
  A1= squeeze( sum( reshape(A, 40, [], 1) ) );
  B1=squeeze( sum( reshape(B, 40, [], 1) ) );
  C1=A1-B1;
  subplot(3,1,1);
  stem(C1);
  b=[0.69977431651797461 -0.1814575955924495 1.4113120181091672 -0.18145759559244945 0.69977431651797473];
  a=[1 -0.21440197757618362 1.3190484139225416 -0.148513213608716 0.491812237222576];
      y =filter(b,a,C1);
      subplot(3,1,2);
    stem(y);
   d=[0.0000089848614639706426 0.0000035939445855882617 0.0000053909168783823964 0.0000035939445855882685 0.00000089848614639706807]
   e=[1 -3.8358255406473472 5.5208191366222277 -3.5335352194630145 0.8485559996647685]
   z=filter(d,e,C1);
    subplot(3,1,3);
   stem(z);

code is working... im using two filters here... notch and low pass filter..i have to find the statistics of the plot.... standard deviation and mean... what i should do???

Answer 2

[Jos (10584)]

In cases when the total number of elements is not divisible by the size of the smaller groups, and reshape cannot be used, this trick with accumarray may be useful:

V = 1:10 ;
n = 3 ;
rem(numel(V),n) % :-(

ix = floor((0:numel(V)-1)/3) ;
R = accumarray(ix, V ,@sum)