diff options
Diffstat (limited to 'numpy/core/fromnumeric.py')
| -rw-r--r-- | numpy/core/fromnumeric.py | 76 |
1 files changed, 68 insertions, 8 deletions
diff --git a/numpy/core/fromnumeric.py b/numpy/core/fromnumeric.py index 948c2139d..75bcedd81 100644 --- a/numpy/core/fromnumeric.py +++ b/numpy/core/fromnumeric.py @@ -1812,7 +1812,7 @@ def clip(a, a_min, a_max, out=None): return _wrapfunc(a, 'clip', a_min, a_max, out=out) -def sum(a, axis=None, dtype=None, out=None, keepdims=np._NoValue): +def sum(a, axis=None, dtype=None, out=None, keepdims=np._NoValue, initial=np._NoValue): """ Sum of array elements over a given axis. @@ -1851,6 +1851,10 @@ def sum(a, axis=None, dtype=None, out=None, keepdims=np._NoValue): `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 + Starting value for the sum. See `~numpy.ufunc.reduce` for details. + + .. versionadded:: 1.15.0 Returns ------- @@ -1898,6 +1902,10 @@ def sum(a, axis=None, dtype=None, out=None, keepdims=np._NoValue): >>> np.ones(128, dtype=np.int8).sum(dtype=np.int8) -128 + You can also start the sum with a value other than zero: + + >>> np.sum([10], initial=5) + 15 """ if isinstance(a, _gentype): # 2018-02-25, 1.15.0 @@ -1912,7 +1920,8 @@ def sum(a, axis=None, dtype=None, out=None, keepdims=np._NoValue): return out return res - return _wrapreduction(a, np.add, 'sum', axis, dtype, out, keepdims=keepdims) + return _wrapreduction(a, np.add, 'sum', axis, dtype, out, keepdims=keepdims, + initial=initial) def any(a, axis=None, out=None, keepdims=np._NoValue): @@ -2209,7 +2218,7 @@ def ptp(a, axis=None, out=None, keepdims=np._NoValue): return _methods._ptp(a, axis=axis, out=out, **kwargs) -def amax(a, axis=None, out=None, keepdims=np._NoValue): +def amax(a, axis=None, out=None, keepdims=np._NoValue, initial=np._NoValue): """ Return the maximum of an array or maximum along an axis. @@ -2241,6 +2250,13 @@ def amax(a, axis=None, out=None, keepdims=np._NoValue): 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 `~numpy.ufunc.reduce` for details. + + .. versionadded:: 1.15.0 + + Returns ------- amax : ndarray or scalar @@ -2293,11 +2309,26 @@ def amax(a, axis=None, out=None, keepdims=np._NoValue): >>> 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], [10]], 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([5], initial=6) + 6 + >>> max([5], default=6) + 5 """ - return _wrapreduction(a, np.maximum, 'max', axis, None, out, keepdims=keepdims) + return _wrapreduction(a, np.maximum, 'max', axis, None, out, keepdims=keepdims, + initial=initial) -def amin(a, axis=None, out=None, keepdims=np._NoValue): +def amin(a, axis=None, out=None, keepdims=np._NoValue, initial=np._NoValue): """ Return the minimum of an array or minimum along an axis. @@ -2329,6 +2360,12 @@ def amin(a, axis=None, out=None, keepdims=np._NoValue): sub-class' method does not implement `keepdims` any exceptions will be raised. + initial : scalar, optional + The maximum value of an output element. Must be present to allow + computation on empty slice. See `~numpy.ufunc.reduce` for details. + + .. versionadded:: 1.15.0 + Returns ------- amin : ndarray or scalar @@ -2381,8 +2418,22 @@ def amin(a, axis=None, out=None, keepdims=np._NoValue): >>> np.nanmin(b) 0.0 + >>> np.min([[-50], [10]], axis=-1, initial=0) + array([-50, 0]) + + Notice that the initial value is used as one of the elements for which the + minimum is determined, unlike for the default argument Python's max + function, which is only used for empty iterables. + + Notice that this isn't the same as Python's ``default`` argument. + + >>> np.min([6], initial=5) + 5 + >>> min([6], default=5) + 6 """ - return _wrapreduction(a, np.minimum, 'min', axis, None, out, keepdims=keepdims) + return _wrapreduction(a, np.minimum, 'min', axis, None, out, keepdims=keepdims, + initial=initial) def alen(a): @@ -2418,7 +2469,7 @@ def alen(a): return len(array(a, ndmin=1)) -def prod(a, axis=None, dtype=None, out=None, keepdims=np._NoValue): +def prod(a, axis=None, dtype=None, out=None, keepdims=np._NoValue, initial=np._NoValue): """ Return the product of array elements over a given axis. @@ -2458,6 +2509,10 @@ def prod(a, axis=None, dtype=None, out=None, keepdims=np._NoValue): `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 starting value for this product. See `~numpy.ufunc.reduce` for details. + + .. versionadded:: 1.15.0 Returns ------- @@ -2515,8 +2570,13 @@ def prod(a, axis=None, dtype=None, out=None, keepdims=np._NoValue): >>> np.prod(x).dtype == int True + You can also start the product with a value other than one: + + >>> np.prod([1, 2], initial=5) + 10 """ - return _wrapreduction(a, np.multiply, 'prod', axis, dtype, out, keepdims=keepdims) + return _wrapreduction(a, np.multiply, 'prod', axis, dtype, out, keepdims=keepdims, + initial=initial) def cumprod(a, axis=None, dtype=None, out=None): |