numpy.cumprod¶

numpy.cumprod(a,axis=None,dtype=None,out=None)[source]¶

Return the cumulative product of elements along a given axis.

Parameters:

a:array_like Input array. axis:int, optional Axis along which the cumulative product is computed. By defaultthe input is flattened. dtype:dtype, optional Type of the returned array, as well as of the accumulator in whichthe elements are multiplied. Ifdtype is not specified, itdefaults to the dtype ofa, unlessa has an integer dtype witha precision less than that of the default platform integer. Inthat case, the default platform integer is used instead. out:ndarray, optional Alternative output array in which to place the result. It musthave the same shape and buffer length as the expected outputbut the type of the resulting values will be cast if necessary.

Returns:

cumprod:ndarray A new array holding the result is returned unlessout isspecified, in which case a reference to out is returned.

See also

numpy.doc.ufuncs

Section “Output arguments”

Notes

Arithmetic is modular when using integer types, and no error israised on overflow.

Examples

>>>a=np.array([1,2,3])>>>np.cumprod(a)# intermediate results 1, 1*2...# total product 1*2*3 = 6array([1, 2, 6])>>>a=np.array([[1,2,3],[4,5,6]])>>>np.cumprod(a,dtype=float)# specify type of outputarray([   1.,    2.,    6.,   24.,  120.,  720.])

The cumulative product for each column (i.e., over the rows) ofa:

>>>np.cumprod(a,axis=0)array([[ 1,  2,  3],       [ 4, 10, 18]])

The cumulative product for each row (i.e. over the columns) ofa:

>>>np.cumprod(a,axis=1)array([[  1,   2,   6],       [  4,  20, 120]])