datatable.rowfirst()

datatable.

rowfirst

(

*cols

)

sourcetests

For each row, find the first non-missing value in cols. If all values in a row are missing, then this function will also produce a missing value.

Parameters

cols

FExpr

Input columns.

return

FExpr

f-expression consisting of one column and the same number of rows as in cols.

except

TypeError

The exception is raised when input columns have incompatible types.

Examples

from datatable import dt, f DT = dt.Frame({"A": [1, 1, 2, 1, 2], "B": [None, 2, 3, 4, None], "C": [True, False, False, True, True]}) DT

	A	B	C
	int32	int32	bool8
0	1	NA	1
1	1	2	0
2	2	3	0
3	1	4	1
4	2	NA	1

5 rows × 3 columns

DT[:, dt.rowfirst(f[:])]

	C0
	int32
0	1
1	1
2	2
3	1
4	2

5 rows × 1 column

DT[:, dt.rowfirst(f['B', 'C'])]

	C0
	int32
0	1
1	2
2	3
3	4
4	1

5 rows × 1 column

See Also

• rowlast() – find the last non-missing value row-wise.