Efficient methods and techniques for processing CSV files in Python

Python provides an efficient csv module to process CSV files. You can do this by following these steps: Install the csv module. Use csv.reader() to read CSV files. Efficiently process large files line by line. Read and write CSV files in memory for faster processing. Use csv.writer() to write out a CSV file. Process CSV files in different formats through dialects. Customize delimiters and quotes to read non-standard CSV files.

Efficient methods and techniques for processing CSV files in Python

Practical case: reading and analyzing sales data CSV files

1. Install the csv module

Use Python's pip Install csv Module:

pip install csv

2. Read CSV file

Use csv.reader() Read CSV file:

import csv

with open('sales_data.csv', 'r') as csv_file:
    csv_reader = csv.reader(csv_file)
    for row in csv_reader:
        print(row)  # 打印每一行数据

3. Line-by-line processing

Use the line-by-line processing generator to process large files more efficiently:

import csv

with open('sales_data.csv', 'r') as csv_file:
    csv_reader = csv.reader(csv_file)
    for row in csv_reader:
        process_row(row)  # 调用自定义函数处理每一行

4. Read and write CSV in memory

Use the StringIO class to load CSV data into memory for quick processing:

import csv
from io import StringIO

csv_data = """
1,John Doe,100
2,Jane Smith,200
"""

csv_file = StringIO(csv_data)
csv_reader = csv.reader(csv_file)
for row in csv_reader:
    print(row)

5. Write out the CSV file

Use csv.writer() to write out the CSV file:

import csv

with open('output.csv', 'w', newline='') as csv_file:
    csv_writer = csv.writer(csv_file)
    csv_writer.writerow(['ID', 'Name', 'Sales'])
    csv_writer.writerow([1, 'John Doe', 100])

6. Use dialects

to handle different dialects (such as Excel or Google Sheets) CSV file:

import csv

with open('sales_data.csv', 'r') as csv_file:
    csv_reader = csv.reader(csv_file, dialect='excel')
    for row in csv_reader:
        print(row)

7. Set delimiter and quote character

Custom delimiter and quote character:

import csv

with open('custom_data.csv', 'r') as csv_file:
    csv_reader = csv.reader(csv_file, delimiter=';', quotechar='"')
    for row in csv_reader:
        print(row)

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