nlcpy.sum
- nlcpy.sum(a, axis=None, dtype=None, out=None, keepdims=nlcpy._NoValue, initial=nlcpy._NoValue, where=nlcpy._NoValue)
Sum of array elements over a given axis.
- Parameters
- aarray_like
Elements to sum.
- axisNone or int or tuple of ints, optional
Axis or axes along which a sum is performed. The default, axis=None, will sum all of the elements of the input array. If axis is negative it counts from the last to the first axis. If axis is a tuple of ints, a sum is performed on all of the axes specified in the tuple instead of a single axis or all the axes as before.
- dtypedtype, optional
The type used to represent the intermediate results. Defaults to the dtype of the output array if this is provided. If out is not provided, the dtype of a is used unless a has nlcpy.int32 or nlcpy.uint32. In that case, nlcpy.int64 or nlcpy.uint64 is used.
- outndarray, optional
Alternative output array in which to place the result. It must have the same shape as the expected output, but the type of the output values will be cast if necessary.
- keepdimsbool, 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 array.
- initialscalar, optional
The value with which to start the reduction. Defaults to 0. If None is given, the first element of the reduction is used, and an error is thrown if the reduction is empty.
- wherearray_like of bool, optional
A boolean array which is broadcasted to match the dimensions of a, and selects elements to include in the reduction.
- Returns
- sum_along_axisndarray
An array with the same shape as a, with the specified axis removed. If a is a 0-d array, or if axis is None, this function returns the result as a 0-dimention array. If an output array is specified, a reference to out is returned.
参考
注釈
nlcpy.reduce.add is called in this function.
Arithmetic is modular when using integer types, and no error is raised on overflow.
The sum of an empty array is the neutral element 0:
>>> import nlcpy as vp >>> vp.sum([]) array(0.)
制限事項
If an ndarray is passed to
where
andwhere.shape != a.shape
, NotImplementedError occurs.If an ndarray is passed to
out
andout.shape != sum_along_axis.shape
, NotImplementedError occurs.
Examples
>>> import nlcpy as vp >>> vp.sum([0.5, 1.5]) array(2.) >>> vp.sum([0.5, 0.7, 0.2, 1.5], dtype=vp.int32) array(1, dtype=int32) >>> vp.sum([[0, 1], [0, 5]]) array(6) >>> vp.sum([[0, 1], [0, 5]], axis=0) array([0, 6]) >>> vp.sum([[0, 1], [0, 5]], axis=1) array([1, 5])
You can also start the sum with a value other than zero:
>>> vp.sum([10], initial=5) array(15)