Missing values - Running average
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First of, I hvae this huge dataset, with 84000 rows and 24 cols. However, there are missing data cells within this excel file. Most of these cells have a value above and below them. Now I wanted to fill this gap, with the running average from above and below this cell.
How can I do this, in a less time-consuming way - New to Matlab.
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Image Analyst
2016-12-28
That's not huge - it's only about a tenth the size of a typical digital image. Anyway, you will get nan in the data where the Excel cell is empty. So use conv2() and isnan() to replace the missing ones. Assuming there is only one missing cell, not a string of them, do something like this:
%data = rand(18, 24); % Create sample/test data.
%data(5, 2) = nan;
data = xlsread(filename);
% Find missing cells.
nanLocations = isnan(data);
% Assign zeros to nan locations
data(nanLocations) = 0;
% Count non-nans
kernel = [1;1;1];
nonNanCounts = conv2(double(~nanLocations), kernel, 'same');
% Sum up values in 3x1 window.
sums = conv2(data, kernel, 'same');
% Divide the sum by the count to get the mean.
meanMatrix = sums ./ nonNanCounts;
% Replace nan's in original data with mean values.
data(nanLocations) = meanMatrix(nanLocations);
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Image Analyst
2016-12-28
0 个投票
Another way is to use the regionfill() function.
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