How to write to an existing excel file without overwriting data (using pandas)?

Question

I use pandas to write to excel file in the following fashion: ``` import pandas writer = pandas.ExcelWriter('Masterfile.xlsx') data_filtered.to_excel(writer, "Main", cols=['Diff1', 'Diff2']) writer.save() ``` Masterfile.xlsx already consists of number of different tabs. However, it does not yet contain "Main". Pandas correctly writes to "Main" sheet, unfortunately it also deletes all other tabs.

Accepted Answer

Pandas docs says it uses openpyxl for xlsx files. Quick look through the code in `ExcelWriter` gives a clue that something like this might work out:

```
import pandas
from openpyxl import load_workbook

book = load_workbook('Masterfile.xlsx')
writer = pandas.ExcelWriter('Masterfile.xlsx', engine='openpyxl') 
writer.book = book

## ExcelWriter for some reason uses writer.sheets to access the sheet.
## If you leave it empty it will not know that sheet Main is already there
## and will create a new sheet.

writer.sheets = dict((ws.title, ws) for ws in book.worksheets)

data_filtered.to_excel(writer, "Main", cols=['Diff1', 'Diff2'])

writer.save()
```

How to write to an existing excel file without overwriting data (using pandas)?

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