Find and delete a double value in matrix
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I have several matrices with Double values. I want to delete(make null) n numbers. For example n=300 and I want to delete 300 values randomly. Here is a part of my code. I'm not sure if it's correct and how to continue it.
totalsize=size(matrixname,1)*size(matrixname,2);
n=totalsize*PER; %number of elements which values should be deleted
r = randi([1 totalsize],1,pen); %find n random elements to be deleted
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James Tursa
am 24 Feb. 2017
Use randperm, not randi. The randperm function will ensure that you do not get duplicate indexes to delete, whereas using randi might produce duplicate indexes. Also, I am assuming PER is a percentage number, so you should use round or floor or ceil on the result of totalsize*PER to ensure it is an integer for downstream processing.
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Jan
am 24 Feb. 2017
Bearbeitet: Jan
am 24 Feb. 2017
totalsize = numel(matrixname);
n = round(totalsize*PER);
index = randperm(totalsize, n); % n eandom distinct values from 1:totalsize
matrixname(index) = 0;
To delete each n.th element:
matrixname(1:n:totalsize) = 0;
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Jan
am 27 Feb. 2017
@Rihanna: The term "delete(make null)" was not clear to me.
Please explain "it seems the last line is not correct" with details. I cannot run your code to check, what's going on. Note that deleting elements in a matrix might conflict with the definition of a matrix, that all columns have the same number of rows and vice versa.
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