numpy.isnan¶
- numpy.isnan(x[, out]) = <ufunc 'isnan'>¶
Test element-wise for NaN and return result as a boolean array.
Parameters: x : array_like
Input array.
Returns: y : ndarray or bool
For scalar input, the result is a new boolean with value True if the input is NaN; otherwise the value is False.
For array input, the result is a boolean array of the same dimensions as the input and the values are True if the corresponding element of the input is NaN; otherwise the values are False.
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
>>> np.isnan(np.nan) True >>> np.isnan(np.inf) False >>> np.isnan([np.log(-1.),1.,np.log(0)]) array([ True, False, False], dtype=bool)