datatable.prod()

datatable.

prod

(

cols

)

sourcetests

Added in version 1.1.0

Calculate the product of values for each column from cols. The product of missing values is calculated as one.

Parameters

cols

FExpr

Input columns.

return

FExpr

f-expression having one row, and the same names and number of columns as in cols. The column stypes are int64 for boolean and integer columns, float32 for float32 columns and float64 for float64 columns.

except

TypeError

The exception is raised when one of the columns from cols has a non-numeric type.

Examples

from datatable import dt, f, by, prod DT = dt.Frame({'A': [1, 1, 2, 1, 2], 'B': [None, 2, 3, 4, 5], 'C': [1, 2, 1, 1, 2]}) DT

	A	B	C
	int32	int32	int32
0	1	NA	1
1	1	2	2
2	2	3	1
3	1	4	1
4	2	5	2

5 rows × 3 columns

Get the product for column A:

DT[:, prod(f.A)]

	A
	int64
0	4

1 row × 1 column

Get the product for multiple columns:

DT[:, prod(f['A', 'B'])]

	A	B
	int64	int64
0	4	120

1 row × 2 columns

In the presence of by(), it returns the product of the specified columns per group:

DT[:, prod(f['A', 'B']), by('C')]

	C	A	B
	int32	int64	int64
0	1	2	12
1	2	2	10

2 rows × 3 columns