# replacing Nan with 0

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Caroline Prekker on 25 Jul 2020
Commented: Walter Roberson on 10 Aug 2022
I have an excel file that I need to replace nan with zeros
I am using this piece of code and am getting error : Array indices must be positive integers or logical values
Error in "isnan(auPoints(r,c)) = 0;
I am not sure how to fix it or what I am doing wrong
for r = 4:1:22
for c = 2:1:29
if isnan(auPoints(r,c))
isnan(auPoints(r,c))
end
end
end

Star Strider on 25 Jul 2020
Try this:
auPoints - fillmissing(auPoints, 'constant',0);
It might be advisable to save the output to a different variable, in order to preserve the original ‘auPoints’ matrix.
See the documentation for fillmissing (R2016b and later versions) for details.

madhan ravi on 25 Jul 2020
Edited: madhan ravi on 25 Jul 2020
auPoints(isnan(auPoints(r, c))) = 0
Caroline Prekker on 25 Jul 2020
I'm not sure where I would put that. It is telling me that c exceeds array bounds
madhan ravi on 25 Jul 2020
Edited: madhan ravi on 26 Jul 2020
Well it’s assumed that c was within the bounds.
Try this: (OBSCURE)
auPoints = subsasgn(auPoints, substruct('()', {isnan(auPoints)}), 0)

jonas on 25 Jul 2020
The line does not work because the left part just returns a logical.
isnan(auPoints(r,c)) = 0
It is similar to writing
isnan(NaN) = 0
...which makes no sense but returns the same error message
For this type of basic operation it is better to make use of logical indexing. For example, if you want to replace all your NaNs with zeros, you can write the following
The first line returns a logical array (1's and 0's) with the same size as the original array. This array is then used to index the original array. Faster and easier than loops.
More about logical indexing and indexing in general here.
Houss Leng on 10 Aug 2022
I have this error Undefined function 'isnan' for input arguments of type 'table'.
Walter Roberson on 10 Aug 2022
https://www.mathworks.com/help/matlab/ref/fillmissing.html like Star Strider suggests