pandas: filter rows of DataFrame with operator chaining

Question

Most operations in pandas can be accomplished with operator chaining (groupby, aggregate, apply, etc), but the only way I

Answer 1

The answer from @lodagro is great. I would extend it by generalizing the mask function as:

def mask(df, f):
  return df[f(df)]

Then you can do stuff like:

df.mask(lambda x: x[0] < 0).mask(lambda x: x[1] > 0)