Pandas indexing confusion
Use df.iloc[1] to select the second row of the dataframe (it uses zero based indexing).  To select the second column, use df.iloc[:, 1] (the : is slice notation to select all rows).
While looking at indexing in pandas, I had some questions which should be simple enough. If df is a sufficiently long DataFrame, then df[1:2] gives the second row, however, df[1] gives an error and df[[1]] gives the second column. Why is that?