Putting many python pandas dataframes to one excel worksheet

Question

It is quite easy to add many pandas dataframes into excel work book as long as it is different worksheets. But, it is somewhat tricky to get many dataframes into one workshe

Answer 1

I would be more inclined to concatenate the dataframes first and then turn that dataframe into an excel format. To put two dataframes together side-by-side (as opposed to one above the other) do this:

writer = pd.ExcelWriter('test.xlsx',engine='xlsxwriter')   # Creating Excel Writer Object from Pandas  
workbook=writer.book
df.to_excel(writer,sheet_name='Validation',startrow=0 , startcol=0)   
new_df = pd.concat([df, another_df], axis=1)
new_df.to_excel(writer,sheet_name='Validation',startrow=0 , startcol=0)   

Answer 2

user3817518: "Please also share if there is another way to put many dataframes into excel using the built-in df.to_excel functionality !!"

Here's my attempt:

Easy way to put together a lot of dataframes on just one sheet or across multiple tabs. Let me know if this works!

-- To test, just run the sample dataframes and the second and third portion of code.

Sample dataframes

import pandas as pd
import numpy as np

# Sample dataframes    
randn = np.random.randn
df = pd.DataFrame(randn(15, 20))
df1 = pd.DataFrame(randn(10, 5))
df2 = pd.DataFrame(randn(5, 10))

Put multiple dataframes into one xlsx sheet

# funtion
def multiple_dfs(df_list, sheets, file_name, spaces):
    writer = pd.ExcelWriter(file_name,engine='xlsxwriter')   
    row = 0
    for dataframe in df_list:
        dataframe.to_excel(writer,sheet_name=sheets,startrow=row , startcol=0)   
        row = row + len(dataframe.index) + spaces + 1
    writer.save()

# list of dataframes
dfs = [df,df1,df2]

# run function
multiple_dfs(dfs, 'Validation', 'test1.xlsx', 1)

Put multiple dataframes across separate tabs/sheets

# function
def dfs_tabs(df_list, sheet_list, file_name):
    writer = pd.ExcelWriter(file_name,engine='xlsxwriter')   
    for dataframe, sheet in zip(df_list, sheet_list):
        dataframe.to_excel(writer, sheet_name=sheet, startrow=0 , startcol=0)   
    writer.save()

# list of dataframes and sheet names
dfs = [df, df1, df2]
sheets = ['df','df1','df2']    

# run function
dfs_tabs(dfs, sheets, 'multi-test.xlsx')

Answer 3

To create the Worksheet in advance, you need to add the created sheet to the sheets dict:

writer.sheets['Validation'] = worksheet

Using your original code:

# Creating Excel Writer Object from Pandas  
writer = pd.ExcelWriter('test.xlsx',engine='xlsxwriter')   
workbook=writer.book
worksheet=workbook.add_worksheet('Validation')
writer.sheets['Validation'] = worksheet
df.to_excel(writer,sheet_name='Validation',startrow=0 , startcol=0)   
another_df.to_excel(writer,sheet_name='Validation',startrow=20, startcol=0) 

---

Explanation

If we look at the pandas function to_excel, it uses the writer's write_cells function:

excel_writer.write_cells(formatted_cells, sheet_name, startrow=startrow, startcol=startcol)

So looking at the write_cells function for xlsxwriter:

def write_cells(self, cells, sheet_name=None, startrow=0, startcol=0):
    # Write the frame cells using xlsxwriter.
    sheet_name = self._get_sheet_name(sheet_name)
    if sheet_name in self.sheets:
        wks = self.sheets[sheet_name]
    else:
        wks = self.book.add_worksheet(sheet_name)
        self.sheets[sheet_name] = wks

Here we can see that it checks for sheet_name in self.sheets, and so it needs to be added there as well.

Answer 4

The answer by Adrian can be simplified as follows

writer = pd.ExcelWriter('test.xlsx',engine='xlsxwriter')
df.to_excel(writer,sheet_name='Validation',startrow=0 , startcol=0)
another_df.to_excel(writer,sheet_name='Validation',startrow=20, startcol=0)

Works for pandas 0.25.3 with python 3.7.6