datatable.sd()

datatable.

sd

(

cols

)

source

Calculate the standard deviation for each column from cols.

Parameters

cols

Expr

Input columns.

return

Expr

f-expression having one row, and the same names and number of columns as in cols. The column stypes are float32 for float32 columns, and float64 for all the other numeric types.

except

TypeError

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

Examples

from datatable import dt, f DT = dt.Frame(A = [0, 1, 2, 3], B = [0, 2, 4, 6]) DT

	A	B
	int32	int32
0	0	0
1	1	2
2	2	4
3	3	6

4 rows × 2 columns

Get the standard deviation of column A:

DT[:, dt.sd(f.A)]

	A
	float64
0	1.29099

1 row × 1 column

Get the standard deviation of columns A and B:

DT[:, dt.sd([f.A, f.B])]

	A	B
	float64	float64
0	1.29099	2.58199

1 row × 2 columns

See Also

• mean() – function to calculate mean values.

• median() – function to calculate median values.