Triangle.pct_chg() always raises AttributeError #1528

Are you on the latest chainladder version?

• Yes, this bug occurs on the latest version.

Describe the bug in words

pct_chg is in the df_passthru list in chainladder/core/pandas.py, so Triangle.pct_chg is created as a call to pd.DataFrame.pct_chg. pandas has no such method; the pandas method is pct_change. Every call fails at runtime. The user guide (docs/user_guide/triangle.ipynb) also lists pct_chg as a supported pass-through.

How can the bug be reproduced?

import chainladder as cl

raa = cl.load_sample("raa")
raa.pct_chg()

# AttributeError: type object 'DataFrame' has no attribute 'pct_chg'. Did you mean: 'pct_change'?

What is the expected behavior?

Triangle.pct_change() should work and match pandas.DataFrame.pct_change on to_frame(). To stay backward compatible, pct_chg could either be kept as a deprecated alias or removed. The user guide table should be updated to match.

Would you be willing to contribute this ticket?

• Yes, absolutely!
• Yes, but I would like some help.
• No.