Correct way to select a specific column from the last row of a Dataframe

Question

I have a dataframe stock_pick and trying to set last row of certain column like

stock_pick.iloc[-1]["Regime"] = 0

This results in the ,

/home/prowler/analysis-toolkit/anaconda2/envs/py3.6/lib/python3.6/site-packages/pandas/core/indexing.py:179: SettingWithCopyWarning: 
A value is trying to be set on a copy of a slice from a DataFrame

See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
  self._setitem_with_indexer(indexer, value)

What is the correct way to pick and assign a value to a specific column in the last row?

Answer 1

You can use get_loc for position of column and thn is posssible use DataFrame.iloc:

stock_pick.iloc[-1, stock_pick.columns.get_loc("Regime")] = 0

Another solution is select by DataFrame.loc and select index by position by [-1]:

stock_pick.loc[stock_pick.index[-1], "Regime"] = 0