pandas.errors.PerformanceWarning

exception pandas.errors.PerformanceWarning

Warning raised when there is a possible performance impact.

See also

DataFrame.set_index

Set the DataFrame index using existing columns.

DataFrame.loc

Access a group of rows and columns by label(s) or a boolean array.

Examples

>>> df = pd.DataFrame(
...     {"jim": [0, 0, 1, 1], "joe": ["x", "x", "z", "y"], "jolie": [1, 2, 3, 4]}
... )
>>> df = df.set_index(["jim", "joe"])
>>> df
          jolie
jim  joe
0    x    1
     x    2
1    z    3
     y    4
>>> df.loc[(1, "z")]  
# PerformanceWarning: indexing past lexsort depth may impact performance.
df.loc[(1, 'z')]
          jolie
jim  joe
1    z        3