Preface
1. Import CSV library
2. Yes CSV Read and write files
2.1 Write... As a list CSV file
2.2 Read... In list form CSV file
2.3 Write... In dictionary form csv file
2.4 Read in dictionary form csv file
Conclusion
PrefaceCSV(Comma-Separated Values) Comma separated values , A text file separated by commas and stored in rows , All values are expressed as string types （ Be careful ： The number is of string type ）. If CSV There are Chinese , Should use utf-8 Coded reading and writing .
1. Import CSV librarypython Chinese vs csv The file has its own library, which can be used , When we want to csv When reading and writing files, you can import them directly .
import csv2. Yes CSV Read and write files 2.1 Write... As a list CSV file grammar ：csv.writer(f)：
writer Support writerow( list ) Single line write , and writerows( Nested list ) Batch write multiple lines , No need to save it manually .
import csvheader = ['name','age','QQ_num','wechat']data = [['suliang','21','787991021','lxzy787991021']]with open ('information.csv','w',encoding='utf-8',newline='') as fp: # Write writer =csv.writer(fp) # Set the first row header writer.writerow(header) # Write data to writer.writerows(data)result ：
2.2 Read... In list form CSV fileBe careful ： When opening a file, you should specify a format of w, Text writing .
When opening a file , Specifies that new rows are not automatically added newline=‘’, Otherwise, one or more blank lines will be written for each line .
grammar ：csv.reader(f, delimiter=‘,’)
reader Generator , Read one line at a time , Each row of data is in list format , Can pass delimiter Parameter specifies the separator
import csvwith open('information.csv',encoding='utf-8')as fp: reader = csv.reader(fp) # Get the title header = next(reader) print(header) # Traversal data for i in reader: print(i)result ：
Be sure to read and write files when necessary , When you are uncertain, you can write an absolute path . To get csv The content needs to be traversed and then output .
2.3 Write... In dictionary form csv filegrammar ：csv.DicWriter(f)：
When writing, you can use writeheader() Write the title , And then use writerow( Dictionary format data row ) or writerows( Multi row data )
import csvheader = ['name','age']data = [{'name':'suliang','age':'21'}, {'name':'xiaoming','age':'22'}, {'name':'xiaohu','age':'25'}]with open ('information.csv','w',encoding='utf-8',newline='') as fp: # Write writer =csv.DictWriter(fp,header) # Write the title writer.writeheader() # Write data to writer.writerows(data)result ：
grammar ：csv.DicReader(f, delimiter=‘,’)
Directly assemble the title and each column of data into an ordered Dictionary （OrderedDict） Format , There is no need to read the header line separately
import csvwith open('information.csv',encoding='utf-8')as fp: reader = csv.DictReader(fp) for i in reader print(i)result ：
attach ：csv Reading and writing mode
r： Open the file read , Can read file information
w： File opened in write mode , Information can be written to the file . If the file exists , Leave blank , Write again
a： Open file in append mode , When opening a file, the pointer can be moved to the end , Create if file does not exist
r+： Open the file read-write , Can read and write files
w+： Eliminate document content , Open the file read-write
a+： Open the file read-write , The file pointer moves to the end
b： Open the file in binary
ConclusionThis article is about in python Read and write to CSV That's all for the details of the document , More about python Reading and writing CSV Please search the previous articles of software development network or continue to browse the relevant articles below. I hope you will support software development network more in the future ！
