How can I approximate a data set from excel and plot over the original set?

Hello all,

-I have a data set in excel of 4 columns, 1st of these is Time. -I would like to reduce/down-sample this set to approximate the curve that it produces by a factor N (other than the time column) -Then I would like plot the original set and the reduced set overlaid, with each of the 3 non-time columns individually, plotted against the time data

I am able to accept the data into Matlab and plot.

I have looked at down-sample,dsplot and a few others but I'm quite unsure which is best for my application

I would very much appreciate being pointed in the right direction.

Best Regards Gavin

Answer 1

[Kirby Fears]

Hi Gavin,

If you're looking to plot every N-th point (reducing the total sample by a factor of N), you can do this very easily with indexing. Try adapting the example below to your needs.

myTime = (1:100)'; % Storing time separately
myData = [sin(myTime), cos(myTime), tan(myTime)]; % Fake data
n = 5; % Sample by taking every nth point
idxSamp = (1:n:size(myTime,1))';
% Plot original data and downsampled data
plot(repmat(myTime,1,size(myData,2)),myData,...
    repmat(myTime(idxSamp),1,size(myData,2)),myData(idxSamp,:));
legend({'s','c','t','down s','down c','down t'});

Hope this helps.

[Gavin Davis]

Hi Kirby. Thank you for your answer!