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Finding columns that contain both integers and NaN

Asked by Ahmed Hamed on 4 Feb 2016
Latest activity Commented on by the cyclist
on 4 Feb 2016
I have a matrix that contain Numerical values (float) and Categorical values (Int)
as
A = 1 NaN 2.2 3.2 4
NaN 7.9 5.1 NaN 5
3 5.5 NaN 4.1 NaN
and I'd like to split it into matrices;
one contains the Int values and the other contains the float values as
it = 1 4
NaN 5
3 NaN
and
flt = NaN 2.2 3.2
7.9 5.1 NaN
5.5 NaN 4.1
i use the following code
int_cols = all( round(A)==A, 1 ); %// logical indexing into integer columns
it = A(:,int_cols);
flt = A(:,~int_cols);
However, NaN isn't equal NaN so it appears in the flt matrix and it = [].
Are there any function that can help?

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2 Answers

Answer by David Young
on 4 Feb 2016

Yes, isnan(x) does what x == NaN would do if NaNs were equal to each other.

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Answer by the cyclist
on 4 Feb 2016

int_cols = all( round(A)==A | isnan(A), 1 ); %// logical indexing into integer columns
it = A(:,int_cols)
flt = A(:,~int_cols)

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If the entries in A are have been computed in prior operations, you might also want to guard against floating point inaccuracies, such as the value "4" actually being 4.0000000000001. You could check for equality to within a specific tolerance, for example.

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