Format several worksheets with xlsxwriter

Question

Since days I am struggling with this problem: I have a large script where a function is exporting tables in an Excel workbook, each table into a different worksheet. Additionally, I want to give format to the worksheets using engine xlsxwriter . I use the instance with pd.ExcelWriter() as writer . This works fine for an Excel workbook with a single sheet: using to_excel the table is exported and immediately I use an ad hoc function I created to format it.

Code structure:

• Global Excel_formatting function that gives format (input: table, sheet name, text strings)

• Script function_tables function (input: dataframe, pathfile) that creates subtables from input dataframe, and uses instance pd.ExcelWriter to:

  -- export the Excel worksheets

  -- call Excel_formatting function to format the worksheets

• At high level, the script calls function_tables

See below the complete code:

    # Global function to format the output tables
    def Excel_formatting(table_input, sheet_name_input, title_in, remark_in, start_row_input):
        # Assign WorkBook and worksheet
        workbook = writer.book
        worksheet = writer.sheets[sheet_name_input]
        start_column = 0
        # Title and remark
        worksheet.write(0, start_column, title_in,
                        workbook.add_format({'bold': True,
                                             'color': '#8B0000',
                                             'size': 18,
                                             'align':'left'}))
        worksheet.write(1, start_column+1, remark_in,
                        workbook.add_format({'italic': True,
                                             'size': 11,
                                             'align':'left'}))
        # Format header (on top of existing header)
        header_format = workbook.add_format({'bold': True,
                                             'text_wrap': False,
                                             'fg_color': '#FF8B8B',
                                             'border': 1,
                                             'align':'center'})
        for col_num, value in enumerate(table_input.columns.values):
            worksheet.write(start_row_input, col_num, value, header_format)
        # Freeze panes / Can also be done with to_excel
        worksheet.freeze_panes(start_row_input+1, 0)
        # Set column width
        end_column = len(table_input.columns)
        worksheet.autofit()
        # Add autofilter to header
        worksheet.autofilter(start_row_input, 0, start_row_input, end_column-1)
        # Add logo (if present, to avoid script error)
        figure_path = 'Logo.JPG'
        if (os.path.exists(figure_path) == True):
            worksheet.insert_image(0, start_column+5, figure_path, {'x_scale': 0.1, 'y_scale': 0.08, 'decorative': True})
        # End of function
        return workbook.close()
    
    def function_tables(x, filename):
        # Here the function creates subtables from input dataframe
        df = x
        Table_1 = df.groupby(['Feature 1'])['Deviation'].sum().reset_index()
        Table_2 = df.groupby(['Feature 2'])['Deviation'].sum().reset_index()
        # ...
        Table_N = df.groupby(['Feature N'])['Deviation'].sum().reset_index()
        
        # Export tables adding new sheets to the same Excel workbook
        with pd.ExcelWriter(filename, engine='xlsxwriter', mode='w') as writer:
            start_row = 2
            Table_1.to_excel(writer, index=True, header=True, sheet_name='Overview Feat.1', startrow=start_row)
            Table_2.to_excel(writer, index=True, header=True, sheet_name='Overview Feat.2', startrow=start_row)
            # ...
            Table_N.to_excel(writer, index=True, header=True, sheet_name='Overview Feat.N', startrow=start_row)
    
            # Formatting the worksheets calling the global function
            title_input_1 = 'Title for overview table 1'
            remark_input_1 = 'Remark Table 1'
            Excel_formatting(Table_2, 'Overview Feat.2', title_input_1, remark_input_1, start_row)
            title_input_2 = 'Title for overview table 2'
            remark_input_2 = 'Remark Table 2'
            # ...
            Excel_formatting(Table_2, 'Overview Feat.N', title_input_2, remark_input_2, start_row)
            title_input_N = 'Title for overview table N'
            remark_input_N = 'Remark Table N'
            Excel_formatting(Table_1, 'Overview Feat.N', title_input_N, remark_input_N, start_row)
    
    # Call section of script
    function_tables(df_input, Path_filename)

I tried also openpyxl, a loop through the tables using a dictionary for the input or not having the formatting function as global but inside the writer instance but all failed, always giving me the same error:

worksheet = writer.sheets[sheet_name_input]
KeyError: 'Overview Feat.1'

It looks that it cannot find the sheetname. Any help? A poorsman alternative will be to create N Excel workbooks and then merged all them, but I prefer not to do so, it must be a more pythonic way to work this, right?

A million thanks!

Answer 1

There are a few issues in the code: the writer object needs to be passed to the Excel_formatting() function, the writer shouldn't be closed in that function, and there are some typos in the titles, captions and variable names.

Here is a working example with those issues fixed. I've added sample data frames, you can replace that with your groupby() code.

import pandas as pd
import os


# Global function to format the output tables
def Excel_formatting(table_input, writer, sheet_name_input, title_in, remark_in, start_row_input):
    # Assign WorkBook and worksheet
    workbook = writer.book
    worksheet = writer.sheets[sheet_name_input]
    start_column = 0
    # Title and remark
    worksheet.write(0, start_column, title_in,
                    workbook.add_format({'bold': True,
                                         'color': '#8B0000',
                                         'size': 18,
                                         'align': 'left'}))
    worksheet.write(1, start_column + 1, remark_in,
                    workbook.add_format({'italic': True,
                                         'size': 11,
                                         'align': 'left'}))
    # Format header (on top of existing header)
    header_format = workbook.add_format({'bold': True,
                                         'text_wrap': False,
                                         'fg_color': '#FF8B8B',
                                         'border': 1,
                                         'align': 'center'})
    for col_num, value in enumerate(table_input.columns.values):
        worksheet.write(start_row_input, col_num, value, header_format)
    # Freeze panes / Can also be done with to_excel
    worksheet.freeze_panes(start_row_input + 1, 0)
    # Set column width
    end_column = len(table_input.columns)
    worksheet.autofit()
    # Add autofilter to header
    worksheet.autofilter(start_row_input, 0, start_row_input, end_column - 1)
    # Add logo (if present, to avoid script error)
    figure_path = 'Logo.JPG'
    if os.path.exists(figure_path):
        worksheet.insert_image(0, start_column + 5, figure_path, {'x_scale': 0.1, 'y_scale': 0.08, 'decorative': True})


def function_tables(x, filename):
    Table_1 = pd.DataFrame({'Data': [11, 12, 13, 14]})
    Table_2 = pd.DataFrame({'Data': [11, 12, 13, 14]})
    # ...
    Table_N = pd.DataFrame({'Data': [11, 12, 13, 14]})

    # Export tables adding new sheets to the same Excel workbook
    with pd.ExcelWriter(filename, engine='xlsxwriter', mode='w') as writer:
        start_row = 2
        Table_1.to_excel(writer, index=True, header=True, sheet_name='Overview Feat.1', startrow=start_row)
        Table_2.to_excel(writer, index=True, header=True, sheet_name='Overview Feat.2', startrow=start_row)
        # ...
        Table_N.to_excel(writer, index=True, header=True, sheet_name='Overview Feat.N', startrow=start_row)

        # Formatting the worksheets calling the global function
        title_input_1 = 'Title for overview table 1'
        remark_input_1 = 'Remark Table 1'
        Excel_formatting(Table_1, writer, 'Overview Feat.1', title_input_1, remark_input_1, start_row)

        title_input_2 = 'Title for overview table 2'
        remark_input_2 = 'Remark Table 2'
        Excel_formatting(Table_2, writer, 'Overview Feat.2', title_input_2, remark_input_2, start_row)

        title_input_N = 'Title for overview table N'
        remark_input_N = 'Remark Table N'
        Excel_formatting(Table_N, writer, 'Overview Feat.N', title_input_N, remark_input_N, start_row)


# Call section of script
function_tables(None, 'test.xlsx')

Output:

However, to make it more generic it would be best to handle the main function in a loop like this:

def function_tables(x, filename):
    writer = pd.ExcelWriter(filename, engine='xlsxwriter')

    Table_1 = pd.DataFrame({'Data': [11, 12, 13, 14]})
    Table_2 = pd.DataFrame({'Data': [11, 12, 13, 14]})
    # ...
    Table_N = pd.DataFrame({'Data': [11, 12, 13, 14]})

    # In a real case you would probably append() these in a loop.
    dfs = [Table_1, Table_2, Table_N]

    for i, df in enumerate(dfs, 1):
        start_row = 2
        df.to_excel(writer, index=True, header=True, sheet_name=f'Overview Feat.{i}', startrow=start_row)

        # Formatting the worksheets calling the global function
        title_input = f'Title for overview table {i}'
        remark_input = f'Remark Table {i}'
        Excel_formatting(df, writer, f'Overview Feat.{i}', title_input, remark_input, start_row)

    writer.close()