bigframes.pandas.DataFrame.eval

DataFrame.eval(expr: str) → DataFrame

Evaluate a string describing operations on DataFrame columns.

Operates on columns only, not specific rows or elements. This allows eval to run arbitrary code, which can make you vulnerable to code injection if you pass user input to this function.

Examples:

>>> df = bpd.DataFrame({'A': range(1, 6), 'B': range(10, 0, -2)})
>>> df
A   B
0  1  10
1  2   8
2  3   6
3  4   4
4  5   2

[5 rows x 2 columns]
>>> df.eval('A + B')
0    11
1    10
2     9
3     8
4     7
dtype: Int64

Assignment is allowed though by default the original DataFrame is not modified.

>>> df.eval('C = A + B')
   A   B   C
0  1  10  11
1  2   8  10
2  3   6   9
3  4   4   8
4  5   2   7

[5 rows x 3 columns]
>>> df
   A   B
0  1  10
1  2   8
2  3   6
3  4   4
4  5   2

[5 rows x 2 columns]

Multiple columns can be assigned to using multi-line expressions:

>>> df.eval(
...     '''
... C = A + B
... D = A - B
... '''
... )
   A   B   C  D
0  1  10  11 -9
1  2   8  10 -6
2  3   6   9 -3
3  4   4   8  0
4  5   2   7  3

[5 rows x 4 columns]

Parameters:

expr (str) – The expression string to evaluate.

Returns:

DataFrame result after the operation.

Return type:

bigframes.pandas.DataFrame