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Opeyemi Kehinde on 5 Dec 2021
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Commented: Opeyemi Kehinde on 10 Dec 2021
Accepted Answer: Walter Roberson
I have a 2160 by 4320 data that has lots of NaN. How do I make matlab ignore the NaNs (i.e making them an empty entry, not zero) and still maintain the same size of the data size
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Accepted Answer
Walter Roberson on 5 Dec 2021
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A=randi(500,5,5);
A(A<100)=nan
A = 5×5
138 207 415 446 134 NaN 437 153 NaN 449 119 443 141 127 NaN 294 235 NaN 336 149 NaN 155 235 314 264
Ac = num2cell(A)
Ac = 5×5 cell array
{[138]} {[207]} {[415]} {[446]} {[134]} {[NaN]} {[437]} {[153]} {[NaN]} {[449]} {[119]} {[443]} {[141]} {[127]} {[NaN]} {[294]} {[235]} {[NaN]} {[336]} {[149]} {[NaN]} {[155]} {[235]} {[314]} {[264]}
Ac(isnan(A)) = {[]}
Ac = 5×5 cell array
{[ 138]} {[207]} {[ 415]} {[ 446]} {[ 134]} {0×0 double} {[437]} {[ 153]} {0×0 double} {[ 449]} {[ 119]} {[443]} {[ 141]} {[ 127]} {0×0 double} {[ 294]} {[235]} {0×0 double} {[ 336]} {[ 149]} {0×0 double} {[155]} {[ 235]} {[ 314]} {[ 264]}
Ac is now the same size as A, but the nan entries have been made empty.
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More Answers (1)
Matt J on 5 Dec 2021
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It depends on the operation. If you are taking the maximum of each data colum, for example, the NaNs are already ignored, e.g.,
A=randi(500,5,5);
A(A<100)=nan
A = 5×5
156 367 474 104 134 395 166 128 NaN 108 478 360 196 392 387 160 150 NaN 439 190 336 NaN 219 148 330
maximum = max(A)
maximum = 1×5
478 367 474 439 387
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Opeyemi Kehinde on 5 Dec 2021
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https://webchat.mathworks.com/matlabcentral/answers/1603735-how-to-make-nan-data-an-empty-entry#comment_1870040
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I want to create a new variable of the same size and data but this new variable should show blanks/nothing in the places where nan occured. Something like find(isnan(var))=[]
Matt J on 6 Dec 2021
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No, you can't do that. Some place holder to mark missing data will be present in any Matlab array type.
Walter Roberson on 6 Dec 2021
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https://webchat.mathworks.com/matlabcentral/answers/1603735-how-to-make-nan-data-an-empty-entry#comment_1870180
Well it can be done if it is intended for display only, by constructing a character array and disp() that.
Opeyemi Kehinde on 8 Dec 2021
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https://webchat.mathworks.com/matlabcentral/answers/1603735-how-to-make-nan-data-an-empty-entry#comment_1875365
Thanks for the help, but I don't think I can use it for a mathematical calculation (maybe multiplying with another matching data) in this cell format or plot a graph.
Walter Roberson on 8 Dec 2021
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Suppose that somehow you were able to create a numeric-like matrix that you could do mathematics with, and yet displayed some elements as blanks/nothing. What mathematical properties should be blank/nothing have? For example should [blank*2,5] have the blank be treated as the empty vector, and empty times 2 is empty, and horzcat([], 5) is the scalar 5 ??
Opeyemi Kehinde on 10 Dec 2021
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https://webchat.mathworks.com/matlabcentral/answers/1603735-how-to-make-nan-data-an-empty-entry#comment_1879655
Ok thanks
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