NumPy | mean method
Start your free 7-days trial now!
NumPy's mean(~) method computes the mean value along the specified axis.
Parameters
1. a | array-like
The input array.
2. axislink | None or int or tuple of int | optional
The axis along which to compute the mean. For 2D arrays, the allowed values are as follows:
Axis | Meaning |
|---|---|
0 | Row-wise computation of mean |
1 | Column-wise computation of mean |
None | All values used to compute the mean |
By default, axis=None.
3. dtype | string or type | optional
The data-type to use during the computation of the mean. If the inputs are integers, then float64 is used. Otherwise, the same data-type will be used.
As a best practice, you should specify float64 as dtype since if your input is of type float32, then float32 will be used during the computation of the mean, which would result in less accurate results.
4. out | NumPy array | optional
Instead of creating a new array, you can place the computed mean into the array specified by out.
Return value
If axis is unset, then a scalar is returned. Otherwise, a Numpy array is returned.
Examples
Computing the mean of 1D array
np.mean([1,2,3])
2.0
Computing the mean of 2D array
Consider the following array:
a
array([[1, 2], [3, 4]])
Mean of all values
np.mean(a)
2.5
Mean of each column
np.mean(a, axis=0)
array([2., 3.])
Mean of each row
np.mean(a, axis=1)
array([1.5, 3.5])