numpy.isnan — NumPy v1.11 Manual (original) (raw)
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)