Set specific values to NaN
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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 个评论
Peter Strassmann
2020-10-19
编辑:Peter Strassmann
2020-10-19
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.
采纳的回答
Stephen23
2017-4-13
编辑:Stephen23
2017-4-14
>> 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 个评论
Stephen23
2017-4-14
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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