Define DataFrame lower-right cells in `GSheetsClient.to_frame`

Description

Incorporate a way to bound the cells selected by GSheetsClient.to_frame via a right-most and/or lower-most limit.

Motivation

When defining tables in GSheets, someone may be tempted to define more than one table in the same sheet, as shows the screenshot attached:

In the example above, one table is defined by the range A2:B5 and the other by the range D2:F4.

A user calling to_frame with first_cell_loc="D2" may expect the second table to be returned. Currently, the function will return a DataFrame which has the second table's first column as the first column, but will eventually incorporate all columns in the order that they occur in the second row and treat them as part of the same table.

Proposal

It may be useful to incorporate a mechanism to bound the table's range, which would allow to fetch both tables as the following individual DataFrames:

In [ ]: df1
Out[ ]: 
                 parameter  value
0   percentage_change_roas     10
1  percentage_change_spend     50
2   lowest_cost_percentage     70

In [ ]: df2
Out[ ]: 
     weekday  lower_campaign_spend_change  upper_campaign_spend_change
0     Monday                           50                           20
1    Tuesday                           50                           20
2  Wednesday                           50                           20
3   Thursday                           30                           40
4     Friday                           20                           60
5   Saturday                           20                          100
6     Sunday                           20                          100

in one of two ways:

• Explicitly, through parameters like last_row, last_col, and last_cell_loc. The above DataFrames could then be fetched as:

  • df1 = to_frame(sheet_id, last_col="B")
  • df2 = to_frame(sheet_id, first_cell_loc="D1", last_cell_loc="F8")

• Implicitly, by stopping lecture at all-empty rows and columns. The above DataFrames would be fetched as

  • df1 = to_frame(sheet_id)
  • df2 = to_frame(sheet_id, first_cell_loc="D1")

Drawbacks

• Having two tables in the same sheet may be considered sloppy.
• A completely empty row may be expected by some user. This could be patched by incorporating a boolean parameter such as stop_at_empty_rows set to the proper default.