How to change a Data Series contained with Repeated NaNs to become other sequence of NaNs?
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Tyann Hardyn
el 31 de Dic. de 2021
Comentada: Tyann Hardyn
el 27 de En. de 2022
Hi, community
I want to ask something that is still difficult for me to generate the code in Matlab. The data is simple, that is :
A = [NaN, NaN, 0, 0, 0, NaN, NaN, 0, 0, 0, 0, 0, NaN, NaN, 0, NaN, NaN];
And i just want to re-create the data A, with double NaN unique data, to become :
B = [NaN, 0, 0, 0, 0, NaN, 0, 0, 0, 0, 0, 0, NaN, 0, NaN, 0];
And so on for every double NaN of Data A were changed to become Data B with a single NaN unique data?
Its so difficult for me to create such a code for data A to become data B.... Anyone in Community culd help me in solving my problem here? Thank you so much, im so grateful if someone can help me out.... /.\ /.\ /.\
Respuesta aceptada
Stephen23
el 31 de Dic. de 2021
A = [NaN, NaN, NaN, 0, 0, NaN, NaN, 0, 0, 0, 0, 0, NaN, NaN, NaN, NaN, NaN]
X = diff([isnan(A),false])<0;
A(X) = 0
3 comentarios
Image Analyst
el 1 de En. de 2022
This is the only one that worked. We finally clarified what you want -- that only the last nan in a sequence of nans should be set to zero, regardless of how many nans there are in the sequence (as long as it's 2 or longer). The answers by Chunru and Walter don't work in all cases.
So to give @Stephen the credit for the correct Answer, could you change the Accepted answer to Stephen's? 🙂
Más respuestas (2)
Chunru
el 31 de Dic. de 2021
Editada: Chunru
el 31 de Dic. de 2021
A = [NaN, NaN, 0, 0, 0, NaN, NaN, 0, 0, 0, 0, 0, NaN, NaN, 0, NaN, NaN];
idx = isnan(A);
% any repeated nan will be replaced with 0
A(idx == 1 & diff([0 idx]) == 0) = 0
% replace last nan in sequence with 0
A = [NaN, NaN, NaN, 0, 0, NaN, NaN, 0, 0, 0, 0, 0, NaN, NaN, NaN, NaN, NaN];
idx = isnan(A);
A(diff([idx 0])==-1) = 0
1 comentario
Walter Roberson
el 31 de Dic. de 2021
3 tests to be sure the boundary tests are handled correctly -- ending in double nan, ending in single nan, ending in no nan.
Should probably have similar tests about starting with variable number of nan.
%actual work
DN = @(V) V(~isnan(V) | [~isnan(V(2:end)), true]);
%rest is testing
A = [NaN, NaN, 3, 5, 7, NaN, NaN, 2, 4, 6, 8, 10, NaN, NaN, -3, NaN, NaN]
B = DN(A)
A2 = A(1:end-1)
B2 = DN(A2)
A3 = A(1:end-2)
B3 = DN(A3)
3 comentarios
Image Analyst
el 31 de Dic. de 2021
@Tyann Hardyn you are not converting "the last sequence of NaNs should be converted to zero (0)" What your example actually showed was converting the last NaN of the last sequence of NaNs into a zero. That's an entirely different thing. So which way to you want it.
- the last sequence of NaNs (all of them) should be converted to zero (0)
- the last zero of the last sequence of NaNs (one NaN value -- the final one -- only) should be converted to zero (0)
Case 1 or case 2? And does that still apply if the last NaN sequence doesn't go right up to the very end of the vector?
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