datatable.sum()¶
Calculate the sum of values for each column from cols
. The sum of
the missing values is calculated as zero.
Parameters¶
cols
FExpr
Input 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
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 |
Get the sum of column A:
df[:, dt.sum(f.A)]
A | ||
---|---|---|
int64 | ||
0 | 7 |
Get the sum of multiple columns:
df[:, [dt.sum(f.A), dt.sum(f.B)]]
A | B | ||
---|---|---|---|
int64 | int64 | ||
0 | 7 | 14 |
Same as above, but more convenient:
df[:, dt.sum(f[:2])]
A | B | ||
---|---|---|---|
int64 | int64 | ||
0 | 7 | 14 |
In the presence of by()
, it returns the sum of the specified columns per group:
df[:, [dt.sum(f.A), dt.sum(f.B)], by(f.C)]
C | A | B | ||
---|---|---|---|---|
int32 | int64 | int64 | ||
0 | 1 | 4 | 7 | |
1 | 2 | 3 | 7 |
See Also¶
The content on this page is licensed under the Creative Commons Attribution 4.0 License
(CC BY 4.0) ,
and code samples are licensed under the MIT License.