Remove elements in Matrix

2011 10 12
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I plotted Position vs Time data. The user is then able to click and select points that are bad(noise). No problem so far. What is the best way to remove the selected points from the Position and Time matrices? I have a list of the indices for the points being removed.

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Walter Roberson
Walter Roberson 2011-10-12

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Position(TheIndices) = [];
Time(TheIndices) = [];

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Daniel
Daniel 2011-10-12
I am then left with two vectors... Time and Position. How do I reshape them back to matrices?
Walter Roberson
Walter Roberson 2011-10-12
What are their original shapes? And are you wanting to remove individual points here and there or whole rows or whole columns?
If you want to remove individual points here and there but not whole rows or columns, then you could potentially end up with a prime number of remaining elements, which could not be reshaped in to anything other than a vector.
Removing individual points from a matrix or array is usually more trouble than it is worth. Removing rows or columns is easy.
If you do want to remove an entire row or column, you would use (e.g.)
Position(TheIndices,:) = [];
or
Position(:,TheIndices) = [];
Daniel
Daniel 2011-10-13
"Removing individual points from a matrix or array is usually more trouble than it is worth."
I am interested in removing individual points from a matrix.
I have no problem finding, selecting and removing the points... but I can't remove the points and maintain the shape of the matrix. I was I could delete a value and shift the column up... like in Excel! Just fill the missing value at the end with a zero or something.
My best solution so far is to replace the bad value with NaN. Matlab will not plot NaN... resulting in a gap in the graph. I can omit them when processing the data later in the program.
Any other ideas?
Walter Roberson
Walter Roberson 2011-10-18
if ~isempty(TheIndices)
sz = size(Position);
Position(TheIndices) = [];
Time(TheIndices) = [];
Position(prod(sz)) = 0; %0 fill
Time(prod(sz)) = 0; %0 fill
Position = reshape(Position,sz);
Time = reshape(Time,sz);

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