Future Warnings from Pandas series getitem

The calculate_summary_statistics and rasterhydrograph.format_data functions are generating future warnings:

Would be good to address at some point to avoid generating the warning messages.

From summary stats function:

FutureWarning: Series.__getitem__ treating keys as positions is deprecated. In a future version, integer keys will always be treated as labels (consistent with DataFrame behavior). To access a value by position, use `ser.iloc[pos]`
  summary_dict['Site number'] = str(int(df['site_no'][0])).zfill(8)

From format_data function:

FutureWarning: Series.__getitem__ treating keys as positions is deprecated. In a future version, integer keys will always be treated as labels (consistent with DataFrame behavior). To access a value by position, use `ser.iloc[pos]`
  fut_col = [str(df_out['index_doy'][i]) + '-' +
FutureWarning: Series.__getitem__ treating keys as positions is deprecated. In a future version, integer keys will always be treated as labels (consistent with DataFrame behavior). To access a value by position, use `ser.iloc[pos]`
  str(df_out['index_month_day'][i])