numpy.isnan#

numpy.isnan(x,/,out=None,*,where=True,casting='same_kind',order='K',dtype=None,subok=True[,signature])=<ufunc'isnan'>#

Test element-wise for NaN and return result as a boolean array.

Parameters:
xarray_like

Input array.

outndarray, None, or tuple of ndarray and None, optional

A location into which the result is stored. If provided, it must havea shape that the inputs broadcast to. If not provided or None,a freshly-allocated array is returned. A tuple (possible only as akeyword argument) must have length equal to the number of outputs.

wherearray_like, optional

This condition is broadcast over the input. At locations where thecondition is True, theout array will be set to the ufunc result.Elsewhere, theout array will retain its original value.Note that if an uninitializedout array is created via the defaultout=None, locations within it where the condition is False willremain uninitialized.

**kwargs

For other keyword-only arguments, see theufunc docs.

Returns:
yndarray or bool

True wherex is NaN, false otherwise.This is a scalar ifx is a scalar.

Notes

NumPy uses the IEEE Standard for Binary Floating-Point for Arithmetic(IEEE 754). This means that Not a Number is not equivalent to infinity.

Examples

>>>importnumpyasnp>>>np.isnan(np.nan)True>>>np.isnan(np.inf)False>>>np.isnan([np.log(-1.),1.,np.log(0)])array([ True, False, False])
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