datatable.count()

datatable.

count

(

cols

)

sourcetests

Calculate the number of non-missing values 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. All the returned column stypes are int64.

except

TypeError

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

See Also

• sum() – function to calculate the sum of values.

Examples

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

	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 count of all rows:

df[:, dt.count()]

	count
	int32
0	5

1 row × 1 column

Get the count of column B (note how the null row is excluded from the count result):

df[:, dt.count(f.B)]

	B
	int64
0	4

1 row × 1 column