prod(a, axis=None, dtype=None, keepdims=False, split_every=None, out=None)
This docstring was copied from numpy.prod.
Some inconsistencies with the Dask version may exist.
Arithmetic is modular when using integer types, and no error is raised on overflow. That means that, on a 32-bit platform:
>>> x = np.array([536870910, 536870910, 536870910, 536870910]) # doctest: +SKIP >>> np.prod(x) # doctest: +SKIP 16 # may vary
The product of an empty array is the neutral element 1:
>>> np.prod([]) # doctest: +SKIP 1.0
Input data.
Axis or axes along which a product is performed. The default, axis=None, will calculate the product of all the elements in the input array. If axis is negative it counts from the last to the first axis.
If axis is a tuple of ints, a product is performed on all of the axes specified in the tuple instead of a single axis or all the axes as before.
The type of the returned array, as well as of the accumulator in which the elements are multiplied. The dtype of a is used by default unless a has an integer dtype of less precision than the default platform integer. In that case, if a is signed then the platform integer is used while if a is unsigned then an unsigned integer of the same precision as the platform integer is used.
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.
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 prod
method of sub-classes of :None:None:`ndarray`, however any non-default value will be. If the sub-class' method does not implement keepdims
any exceptions will be raised.
The starting value for this product. See :None:None:`~numpy.ufunc.reduce` for details.
Elements to include in the product. See :None:None:`~numpy.ufunc.reduce` for details.
An array shaped as a but with the specified axis removed. Returns a reference to :None:None:`out` if specified.
Return the product of array elements over a given axis.
ndarray.prod
equivalent method
By default, calculate the product of all elements:
This example is valid syntax, but we were not able to check execution>>> np.prod([1.,2.]) # doctest: +SKIP 2.0
Even when the input array is two-dimensional:
This example is valid syntax, but we were not able to check execution>>> np.prod([[1.,2.],[3.,4.]]) # doctest: +SKIP 24.0
But we can also specify the axis over which to multiply:
This example is valid syntax, but we were not able to check execution>>> np.prod([[1.,2.],[3.,4.]], axis=1) # doctest: +SKIP array([ 2., 12.])
Or select specific elements to include:
This example is valid syntax, but we were not able to check execution>>> np.prod([1., np.nan, 3.], where=[True, False, True]) # doctest: +SKIP 3.0
If the type of x is unsigned, then the output type is the unsigned platform integer:
>>> x = np.array([1, 2, 3], dtype=np.uint8) # doctest: +SKIP
... np.prod(x).dtype == np.uint # doctest: +SKIP True
If x is of a signed integer type, then the output type is the default platform integer:
>>> x = np.array([1, 2, 3], dtype=np.int8) # doctest: +SKIP
... np.prod(x).dtype == int # doctest: +SKIP True
You can also start the product with a value other than one:
This example is valid syntax, but we were not able to check execution>>> np.prod([1, 2], initial=5) # doctest: +SKIP 10See :
The following pages refer to to this document either explicitly or contain code examples using this.
dask.array.reductions.prod
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