Home Backend Development Python Tutorial Example code sharing of how Python operates on Csv files (picture)

Example code sharing of how Python operates on Csv files (picture)

May 14, 2017 pm 12:01 PM

This article mainly introduces the example code of using Python to operate Csv files. It is very practical. Friends in need can refer to it.

csv is the abbreviation of Comma-Separated Values. It is table data stored in the form of a text file. For example, the following table:

can be stored as a csv file. The file content is:

No.,Name,Age,Score
1,mayi,18,99
2,jack,21,89
3,tom,25,95
4,rain,19,80
Copy after login

Assume that the above csv file is saved as "test.csv"

1. Read the file

How to use Python to extract one of the columns like operating Excel, that is A field can be implemented using the csv module that comes with Python:

The first method uses the reader function to receive an iterable object (such as a csv file), can return a generator, from which the content of the csv can be parsed: For example, the following code can read the entire content of the csv, in rows of units:

#!/usr/bin/python3
# -*- conding:utf-8 -*-
author = 'mayi'

import csv

#读
with open("test.csv", "r", encoding = "utf-8") as f:
  reader = csv.reader(f)
  rows = [row for row in reader]

print(rows)
Copy after login

Get:

[['No.', 'Name', 'Age', 'Score'],
 ['1', 'mayi', '18', '99'],
 ['2', 'jack', '21', '89'],
 ['3', 'tom', '25', '95'],
 ['4', 'rain', '19', '80']]
Copy after login

To extract one of the columns, you can use the following code:

#!/usr/bin/python3
# -*- conding:utf-8 -*-
author = 'mayi'

import csv

#读取第二列的内容
with open("test.csv", "r", encoding = "utf-8") as f:
  reader = csv.reader(f)
  column = [row[1] for row in reader]

print(column)
Copy after login

Get:

['Name', 'mayi', 'jack', 'tom', 'rain']
Copy after login

Pay attention to the values ​​read from csv All are of str type. This method requires knowing the sequence number of the column in advance, for example, Name is in column 2, and you cannot query based on the title 'Name'. At this time, you can use the second method:

The second method is to use DictReader, which is similar to the reader function. It receives an iterable object and can return a generator, but each returned cell is placed Within the value of a dictionary, and the key of this dictionary is the title (i.e. column header) of this cell. You can see the structure of DictReader with the following code:

# -*- conding:utf-8 -*-
author = 'mayi'

import csv

#读
with open("test.csv", "r", encoding = "utf-8") as f:
  reader = csv.DictReader(f)
  column = [row for row in reader]

print(column)
Copy after login

Get:

[{'No.': '1', 'Age': '18', 'Score': '99', 'Name': 'mayi'},
 {'No.': '2', 'Age': '21', 'Score': '89', 'Name': 'jack'},
 {'No.': '3', 'Age': '25', 'Score': '95', 'Name': 'tom'},
 {'No.': '4', 'Age': '19', 'Score': '80', 'Name': 'rain'}]
Copy after login

If we want to use DictReader to read a certain column of csv, we can use the column title query:

#!/usr/bin/python3
# -*- conding:utf-8 -*-
author = 'mayi'

import csv

#读取Name列的内容
with open("test.csv", "r", encoding = "utf-8") as f:
  reader = csv.DictReader(f)
  column = [row['Name'] for row in reader]
print(column)
Copy after login

Get:

['mayi', 'jack', 'tom', 'rain']
Copy after login

2. Write file

When reading the file, we read the csv file into the list, and when writing the file, we will Elements are written to a csv file.

#!/usr/bin/python3
# -*- conding:utf-8 -*-
author = 'mayi'

import csv

#写:追加
row = ['5', 'hanmeimei', '23', '81']
out = open("test.csv", "a", newline = "")
csv_writer = csv.writer(out, dialect = "excel")
csv_writer.writerow(row)
Copy after login
Get:

The above is the detailed content of Example code sharing of how Python operates on Csv files (picture). For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Article

R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)
2 weeks ago By 尊渡假赌尊渡假赌尊渡假赌
Repo: How To Revive Teammates
4 weeks ago By 尊渡假赌尊渡假赌尊渡假赌
Hello Kitty Island Adventure: How To Get Giant Seeds
4 weeks ago By 尊渡假赌尊渡假赌尊渡假赌

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

How to solve the permissions problem encountered when viewing Python version in Linux terminal? How to solve the permissions problem encountered when viewing Python version in Linux terminal? Apr 01, 2025 pm 05:09 PM

Solution to permission issues when viewing Python version in Linux terminal When you try to view Python version in Linux terminal, enter python...

How to efficiently copy the entire column of one DataFrame into another DataFrame with different structures in Python? How to efficiently copy the entire column of one DataFrame into another DataFrame with different structures in Python? Apr 01, 2025 pm 11:15 PM

When using Python's pandas library, how to copy whole columns between two DataFrames with different structures is a common problem. Suppose we have two Dats...

Can Python parameter annotations use strings? Can Python parameter annotations use strings? Apr 01, 2025 pm 08:39 PM

Alternative usage of Python parameter annotations In Python programming, parameter annotations are a very useful function that can help developers better understand and use functions...

How do Python scripts clear output to cursor position at a specific location? How do Python scripts clear output to cursor position at a specific location? Apr 01, 2025 pm 11:30 PM

How do Python scripts clear output to cursor position at a specific location? When writing Python scripts, it is common to clear the previous output to the cursor position...

Python hourglass graph drawing: How to avoid variable undefined errors? Python hourglass graph drawing: How to avoid variable undefined errors? Apr 01, 2025 pm 06:27 PM

Getting started with Python: Hourglass Graphic Drawing and Input Verification This article will solve the variable definition problem encountered by a Python novice in the hourglass Graphic Drawing Program. Code...

How to use Python and OCR technology to try to crack complex verification codes? How to use Python and OCR technology to try to crack complex verification codes? Apr 01, 2025 pm 10:18 PM

Exploration of cracking verification codes using Python In daily network interactions, verification codes are a common security mechanism to prevent malicious manipulation of automated programs...

Do Google and AWS provide public PyPI image sources? Do Google and AWS provide public PyPI image sources? Apr 01, 2025 pm 05:15 PM

Many developers rely on PyPI (PythonPackageIndex)...

Python Cross-platform Desktop Application Development: Which GUI Library is the best for you? Python Cross-platform Desktop Application Development: Which GUI Library is the best for you? Apr 01, 2025 pm 05:24 PM

Choice of Python Cross-platform desktop application development library Many Python developers want to develop desktop applications that can run on both Windows and Linux systems...

See all articles