Writing to Excel with to_excel in Pandas - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output file content after running this code?

Consider the following Python code using pandas. What will be the content of the Excel file output.xlsx after running this?

Pandas

import pandas as pd

df = pd.DataFrame({'Name': ['Alice', 'Bob'], 'Age': [25, 30]})
df.to_excel('output.xlsx', index=False)

A Excel file with columns 'Name' and 'Age' and two rows: Alice 25, Bob 30, including row numbers 0 and 1

B Excel file with columns 'Name' and 'Age' and two rows: Alice 25, Bob 30, without row numbers

C Excel file with columns 'Name' and 'Age' but empty rows

D No Excel file is created due to error

💡 Hint

Check the index parameter in to_excel.

Setting index=False means the row numbers are not saved in the Excel file. So only the data columns and rows appear.

❓ data_output

intermediate

How many sheets are created in the Excel file?

Given this code, how many sheets will the Excel file contain?

Pandas

import pandas as pd

with pd.ExcelWriter('multi_sheet.xlsx') as writer:
    pd.DataFrame({'A': [1, 2]}).to_excel(writer, sheet_name='Sheet1')
    pd.DataFrame({'B': [3, 4]}).to_excel(writer, sheet_name='Sheet2')

A 1

B 3

C 0

D 2

💡 Hint

Each to_excel call with a different sheet_name adds a sheet.

Two to_excel calls with different sheet names create two sheets in the Excel file.

🔧 Debug

advanced

What error does this code raise?

What error will this code raise when trying to write a DataFrame to Excel?

Pandas

import pandas as pd

df = pd.DataFrame({'X': [1, 2]})
df.to_excel('file.xlsx', sheet_name='Data', engine='nonexistent_engine')

A ValueError: Unknown engine: nonexistent_engine

B FileNotFoundError: file.xlsx not found

C TypeError: to_excel() got an unexpected keyword argument 'engine'

D No error, file is created successfully

💡 Hint

Check if the engine name is valid for pandas Excel writing.

The engine parameter must be a valid Excel writer engine. 'nonexistent_engine' is invalid, so pandas raises a ValueError.

🚀 Application

advanced

Which option correctly appends a DataFrame to an existing Excel sheet?

You want to add new rows to an existing Excel sheet without deleting the old data. Which code snippet achieves this?

A Use <code>mode='a'</code> in <code>ExcelWriter</code> and <code>if_sheet_exists='overlay'</code> to append rows.

B Use <code>mode='a'</code> and <code>if_sheet_exists='replace'</code> to append rows.

C Use <code>mode='a'</code> and <code>if_sheet_exists='overlay'</code> to replace the sheet completely.

D Use <code>mode='w'</code> in <code>ExcelWriter</code> to overwrite the file and add new rows.

💡 Hint

Appending means adding data without deleting existing content.

Using mode='a' opens the file in append mode, and if_sheet_exists='overlay' allows adding rows without deleting existing ones.

🧠 Conceptual

expert

What happens if you write a DataFrame with a MultiIndex to Excel without specifying index=False?

Consider a DataFrame with a MultiIndex. What will the Excel output look like if you call to_excel without index=False?

A The MultiIndex is ignored and only data columns are written.

B The MultiIndex is flattened automatically and written as a single column.

C The MultiIndex levels are written as multiple columns on the left, showing the index hierarchy.

D The code raises a TypeError because MultiIndex is not supported.

💡 Hint

Think about how pandas represents MultiIndex in Excel output.

By default, pandas writes each level of the MultiIndex as separate columns on the left side in Excel, preserving the index structure.