Random picking of adjacent data points
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Hi,
May someone help me
I have data in one column and want to randomly pick adjacent 48 data points for 1000 times. For example, we have 10 data point (1, 2,3, 4,5,6,7,8,9,10) and we randomly pick 3 adjacent data points 5 times.
May some one help me ...
Thank you.
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Accepted Answer
Image Analyst
on 29 Aug 2020
Try this:
data = [1:50000]'; % Whatever.....
% Define general parameters for getting the samples:
numElements = size(data, 1)
numAdjacent = 48
numSubsets = 1000
% Now do the iterations to get each of the 1000 subsets.
for k = 1 : numSubsets
% Get the first index at random. Don't get within numAdjacent of the end though!
firstIndex = randi(numElements - numAdjacent + 1);
% Now get the second index which will make the subset have adjacent indexes.
secondIndex = firstIndex + numAdjacent - 1;
% Get one subset of 48 adjacent data samples.
theseData = data(firstIndex : secondIndex);
% Now do something with this set of adjacent elements.
end
5 Comments
Image Analyst
on 29 Aug 2020
You said "I have data set of 50000 enteries and I want to pick 1000 random subsets having 48 adjacent enteries." You did not tell us that you wanted those subsets stored in a 2-D array. Well I'm sure you've already done it by now, but anyway, here is how I created a matrix of 1000 columns and put each subset into its appropriate column:
data = [1:50000]'; % Whatever.....
% Define general parameters for getting the samples:
numElements = size(data, 1)
numAdjacent = 48
numSubsets = 1000
% Create an output array with 1000 columns.
output = zeros(numAdjacent, numSubsets);
% Now do the iterations to get each of the 1000 subsets.
for k = 1 : numSubsets
% Get the first index at random. Don't get within numAdjacent of the end!
firstIndex = randi(numElements - numAdjacent);
% Now get the second index which will make the subset adjacent.
secondIndex = firstIndex + numAdjacent - 1;
fprintf('Subset %d goes from index %d to index %d.\n', k, firstIndex, secondIndex);
% Get one subset of 48 adjacent data samples.
theseData = data(firstIndex : secondIndex);
% Now store this set of adjacent elements into our output array.
output(:, k) = theseData;
end
More Answers (1)
madhan ravi
on 29 Aug 2020
Edited: madhan ravi
on 29 Aug 2020
datasets = num2cell(reshape(data(randperm(48e3)), [], 1e3), 1);
%celldisp(datasets)
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