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pandas.DataFrame.eval

DataFrame.eval(expr, inplace=False, **kwargs)[source]

Evaluate an expression in the context of the calling DataFrame instance.

Parameters:

expr : string

The expression string to evaluate.

inplace : bool, default False

If the expression contains an assignment, whether to perform the operation inplace and mutate the existing DataFrame. Otherwise, a new DataFrame is returned.

New in version 0.18.0.

kwargs : dict

See the documentation for eval() for complete details on the keyword arguments accepted by query().

Returns:

ret : ndarray, scalar, or pandas object

Notes

For more details see the API documentation for eval(). For detailed examples see enhancing performance with eval.

Examples

>>> from numpy.random import randn
>>> from pandas import DataFrame
>>> df = pd.DataFrame(randn(10, 2), columns=list('ab'))
>>> df.eval('a + b')
>>> df.eval('c = a + b')
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