BUG: query modifies the frame when you compare with = · Issue #8664 · pandas-dev/pandas (original) (raw)

@TomAugspurger

I messed up and used = instead of == in a query.

df = pd.DataFrame({'a': [1, 2, 3], 'b': ['a', 'b', 'c']}) df.query('a=1')

That raises a ValueError. But df was modified.

In [15]: df Out[15]: a b 0 1 a 1 1 b 2 1 c

versions:

pandas: 0.15.0-6-g403f38d
bottleneck: None
tables: None
numexpr: 2.3.1

Can't look right now.