amax(a, axis=None, out=None, keepdims=<no value>, initial=<no value>, where=<no value>)¶
Return the maximum of an array or maximum along an axis.
- a : array_like
- axis : None or int or tuple of ints, optional
Axis or axes along which to operate. By default, flattened input is used.
New in version 1.7.0.
If this is a tuple of ints, the maximum is selected over multiple axes, instead of a single axis or all the axes as before.
- out : ndarray, optional
Alternative output array in which to place the result. Must be of the same shape and buffer length as the expected output. See
doc.ufuncs(Section “Output arguments”) 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 input array.
If the default value is passed, then keepdims will not be passed through to the
amaxmethod of sub-classes of
ndarray, however any non-default value will be. If the sub-class’ method does not implement keepdims any exceptions will be raised.
- initial : scalar, optional
The minimum value of an output element. Must be present to allow computation on empty slice. See
New in version 1.15.0.
- where : array_like of bool, optional
Elements to compare for the maximum. See
New in version 1.17.0.
- amax : ndarray or scalar
Maximum of a. If axis is None, the result is a scalar value. If axis is given, the result is an array of dimension
a.ndim - 1.
- The minimum value of an array along a given axis, propagating any NaNs.
- The maximum value of an array along a given axis, ignoring any NaNs.
- Element-wise maximum of two arrays, propagating any NaNs.
- Element-wise maximum of two arrays, ignoring any NaNs.
- Return the indices of the maximum values.
NaN values are propagated, that is if at least one item is NaN, the corresponding max value will be NaN as well. To ignore NaN values (MATLAB behavior), please use nanmax.
amaxfor element-wise comparison of 2 arrays; when
maximum(a, a)is faster than
>>> a = np.arange(4).reshape((2,2)) >>> a array([[0, 1], [2, 3]]) >>> np.amax(a) # Maximum of the flattened array 3 >>> np.amax(a, axis=0) # Maxima along the first axis array([2, 3]) >>> np.amax(a, axis=1) # Maxima along the second axis array([1, 3]) >>> np.amax(a, where=[False, True], initial=-1, axis=0) array([-1, 3]) >>> b = np.arange(5, dtype=float) >>> b = np.NaN >>> np.amax(b) nan >>> np.amax(b, where=~np.isnan(b), initial=-1) 4.0 >>> np.nanmax(b) 4.0
You can use an initial value to compute the maximum of an empty slice, or to initialize it to a different value:
>>> np.max([[-50], ], axis=-1, initial=0) array([ 0, 10])
Notice that the initial value is used as one of the elements for which the maximum is determined, unlike for the default argument Python’s max function, which is only used for empty iterables.
>>> np.max(, initial=6) 6 >>> max(, default=6) 5