Set specific values to NaN
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Sascha Winter
il 13 Apr 2017
Modificato: Peter Strassmann
il 19 Ott 2020
Hello everyone
My problem is as follows. I have a matrix like this for example:
A = [1 2 3 4 5 6 6 6 6;
2 4 3 5 4 6 7 7 7;
5 4 4 4 3 7 8 8 8;
2 1 3 3 3 3 3 3 5]'
Now i want to get a matrix which deletes the values which are similar (starting with the second) untill the end of the column. So columns 1, 2, 3 should delete some values while column 4 shouldn't delete any numbers.
At the end the matrix should look like this
A = [1 2 3 4 5 6 NaN NaN NaN;
2 4 3 5 4 6 7 NaN NaN;
5 4 4 4 3 7 8 NaN NaN;
2 1 3 3 3 3 3 3 5]'
I hope you get my problem. Thanks in Advance.
1 Commento
Peter Strassmann
il 19 Ott 2020
Modificato: Peter Strassmann
il 19 Ott 2020
Be aware that NaN values are only defined for data with single or double precision! It is resets integers to zero, e.g. uint8, int8.
rng(1);
A=randi([0,8], [100,1], "int8");
%A=double(A);
A(A>2)=nan;
If you want to associate NaN values to such data, you have to convert them first (before the remapping) with single(A) or double(A) into values with the according precision.
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Stephen23
il 13 Apr 2017
Modificato: Stephen23
il 14 Apr 2017
>> A = [1,2,5,2;2,4,4,1;3,3,4,3;4,5,4,3;5,4,3,3;6,6,7,3;6,7,8,3;6,7,8,3;6,7,8,5];
>> idx = cumprod(double(diff(flipud(A))==0),1);
>> idx(end+1,:) = false;
>> idx = logical(flipud(idx));
>> A(idx) = NaN
A =
1 2 5 2
2 4 4 1
3 3 4 3
4 5 4 3
5 4 3 3
6 6 7 3
NaN 7 8 3
NaN NaN NaN 3
NaN NaN NaN 5
5 Commenti
Stephen23
il 14 Apr 2017
Try this:
A = [1,2,3,4,5,6,6,6,6; 3,4,4,4,5,6,6,2,1; NaN,NaN,2,4,5,6,6,6,6; 1,2,2,2,2,2,NaN,NaN,NaN; NaN,NaN,NaN,NaN,NaN,NaN,NaN,NaN,NaN]'
idx = diff(flipud(A));
idx = cumprod(double(idx==0|isnan(idx)),1);
idx(end+1,:) = isnan(A(1,:));
idx = logical(flipud(idx));
A(idx) = NaN
which outputs this:
A =
1 3 NaN 1 NaN
2 4 NaN 2 NaN
3 4 2 NaN NaN
4 4 4 NaN NaN
5 5 5 NaN NaN
6 6 6 NaN NaN
NaN 6 NaN NaN NaN
NaN 2 NaN NaN NaN
NaN 1 NaN NaN NaN
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