Optimize reading large Excel files with Pandas

Last update on April 09 2025 12:57:30 (UTC/GMT +8 hours)

20. Optimized Excel File Reading

Write a Pandas program to optimize the performance of reading a large Excel file into a DataFrame by specifying data types and using the 'usecols' parameter.

Sample Solution :

Python Code :

# Import necessary libraries
import pandas as pd

# Specify the path to the large Excel file
file_path = 'large_excel_file.xlsx'

# Define the data types for the columns
dtypes = {
    'Column1': 'int64',
    'Column2': 'float64',
    'Column3': 'object',
    # Add more column types as needed
}

# Define the columns to read
usecols = ['Column1', 'Column2', 'Column3']

# Use read_excel with specified data types and columns to read
df = pd.read_excel(file_path, dtype=dtypes, usecols=usecols)

# Display the DataFrame
print(df.head())

Output:

   Column1  Column2 Column3
0        1      1.1    abcd
1        2      1.2    abcd
2        3      1.3    abcd
3        4      1.4    abcd
4        5      1.5    abcd

Explanation:

• Import necessary libraries:
• Import pandas.
• Specify the path to the large Excel file:
• The file path is set to a variable.
• Define the data types for the columns:
• A dictionary specifying the data types for each column.
• Define the columns to read:
• A list of column names to be read from the Excel file.
• Read the Excel file:
• Use pd.read_excel with the dtype and usecols parameters to optimize performance.
• Display the DataFrame:
• Print the first few rows of the DataFrame to confirm successful loading.

For more Practice: Solve these Related Problems:

• Write a Pandas program to import a large Excel file using the usecols parameter and specified data types, then measure load time.
• Write a Pandas program to optimize reading an Excel file by setting data types and compare the performance with default reading.
• Write a Pandas program to load a subset of columns from a large Excel file using usecols and report the memory usage difference.
• Write a Pandas program to benchmark the performance of reading an Excel file with optimized parameters versus reading the entire file without optimizations.

Python-Pandas Code Editor:

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