# jax.numpy.nanmean¶

jax.numpy.nanmean(a, axis=None, dtype=None, out=None, keepdims=False)[source]

Compute the arithmetic mean along the specified axis, ignoring NaNs.

LAX-backend implementation of nanmean(). Original docstring below.

Returns the average of the array elements. The average is taken over the flattened array by default, otherwise over the specified axis. float64 intermediate and return values are used for integer inputs.

For all-NaN slices, NaN is returned and a RuntimeWarning is raised.

New in version 1.8.0.

Parameters
• a (array_like) – Array containing numbers whose mean is desired. If a is not an array, a conversion is attempted.

• axis ({int, tuple of int, None}, optional) – Axis or axes along which the means are computed. The default is to compute the mean of the flattened array.

• dtype (data-type, optional) – Type to use in computing the mean. For integer inputs, the default is float64; for inexact inputs, it is the same as the input dtype.

• out (ndarray, optional) – Alternate output array in which to place the result. The default is None; if provided, it must have the same shape as the expected output, but the type will be cast if necessary. See ufuncs-output-type for more details.

• keepdims (bool, optional) – If this is set to True, the axes which are reduced are left in the result as dimensions with size one. With this option, the result will broadcast correctly against the original a.

Returns

m – If out=None, returns a new array containing the mean values, otherwise a reference to the output array is returned. Nan is returned for slices that contain only NaNs.

Return type

ndarray, see dtype parameter above

average()

Weighted average

mean()

Arithmetic mean taken while not ignoring NaNs

Notes

The arithmetic mean is the sum of the non-NaN elements along the axis divided by the number of non-NaN elements.

Note that for floating-point input, the mean is computed using the same precision the input has. Depending on the input data, this can cause the results to be inaccurate, especially for float32. Specifying a higher-precision accumulator using the dtype keyword can alleviate this issue.

Examples

>>> a = np.array([[1, np.nan], [3, 4]])
>>> np.nanmean(a)
2.6666666666666665
>>> np.nanmean(a, axis=0)
array([2.,  4.])
>>> np.nanmean(a, axis=1)
array([1.,  3.5]) # may vary