Extracting data from the original data set

I have a data file named roof-disp.out 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.

[Walter Roberson]

This continues from http://www.mathworks.com/matlabcentral/answers/312175-extracting-a-particular-data-from-the-original-data

Answer 1

[Star Strider]

Once again, the easiest way is to interpolate it:

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
rd_new = [ti' Di];                                      % Complete Interpolated ‘rd’ Matrix

[sam moor]

please I am unable to do for .out file that I have uploaded file named roof-disp.zip Please help me on this file

[sam moor]

something is wrong.. in a original data for time 0.02 the corresponding distance is -0.00864 (for your reference I only compare last column distance data) but for rd_new data for time 0.02 the corresponding distance was -0.0017 ( last column data). So something is wrong

[Star Strider]

I’d forgotten you were starting at 0.02 rather than 0.00.

This works:

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