datatable.count()

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
ABC
int32int32int32
01NA1
1122
2231
3141
4252

Get the count of all rows:

df[:, dt.count()]
count
int32
05

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

df[:, dt.count(f.B)]
B
int64
04