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Extracting a particular data from the original data

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sam moor
sam moor on 14 Nov 2016
Edited: Star Strider on 14 Nov 2016
I have a data file named rd.txt attached below. 1st column data refers to time and all other columns refers the corresponding distance. Now I want to extract the data for 0.02,0.04,0.06,...60.00 sec (at a difference of 0.02) from 1st column and corresponding distances. Is there a way to extract data from the original data for a particular values? Your answer is highly appreciated. Thank you.

Accepted Answer

Star Strider
Star Strider on 14 Nov 2016
You may not be reading your data correctly.
This works for me without error:
fidi = fopen('sam moor rd.txt','rt');
Dcell = textscan(fidi, repmat('%f',1,9), 'CollectOutput',1, 'Delimiter',' ');
D = cell2mat(Dcell);
L = size(D,1);
t = D(:,1);
q = length(t > 0)/L;
ti = 0 : 0.02 : max(t); % Interpolation Vector
Di = interp1(t, D(:,2:end), ti, 'linear'); % Interpolated Data
  2 Comments
Star Strider
Star Strider on 14 Nov 2016
I eliminated the first column from the ‘Di’ matrix, because that is the time vector to use for the interpolation.
Adding the ‘rd_new’ assignment will give you the complete, interpolated ‘rd’ matrix:
fidi = fopen('sam moor rd.txt','rt');
Dcell = textscan(fidi, repmat('%f',1,9), 'CollectOutput',1, 'Delimiter',' ');
D = cell2mat(Dcell);
L = size(D,1);
t = D(:,1);
ti = 0.02 : 0.02 : max(t); % Interpolation Vector
Di = interp1(t, D(:,2:end), ti, 'linear'); % Interpolated Data
rd_new = [ti' Di]; % Complete Interpolated ‘rd’ Matrix
EDIT Corrected to begin ‘ti’ at 0.02 rather than 0.00.

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More Answers (1)

Image Analyst
Image Analyst on 14 Nov 2016
I suggest you read the the FAQ on comparing floating point numbers and then use that or try a new function called ismembertol() to find out which rows match your desired times. One might think intersect() might work but because of the FAQ I referred you to, I have my doubts.

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