从 df.query() 字符串获取左右边界

Question

I'm trying to get some extra info from strings that I feed into df.query()

Currently I'm doing data cleaning with:

df = pd.DataFrame({'A': range(1, 6),
                   'B': range(10, 0, -2),
                   'C': range(10, 5, -1)})

query_string = "6 <= B <= 8"

df.query(query_string)

df >>
   A   B    C
1  2   8    9
2  3   6    8

I'm wondering if it would be possible to somehow get the bounds for the query, something like this:

query_string = "6 <= B <= 8"
bounds = some_get_bounds_function(query_string)

bounds >>
(6, 8)

Tried looking around for any ideas better than just parsing the strings myself.

Thanks!

Answer 1

You can split and return the part of the string before the first and after the last space and create a tuple by separating the two with a comma and enclosing with parentheses:

bounds = (int(query_string.split()[0]), int(query_string.split()[-1]))
bounds
(6, 8)

Or better, per your comment:

bounds = (df['B'].min(), df['B'].max())
bounds
(6, 8)