CSV格式读写

Comma-Separated Values 有时也称为字符分隔值，因为分隔字符也可以不是逗号。以,分隔的文件叫csv，以\t分隔的叫tsv

需要注意的一点：分隔符

import csv data=[]
with open(r'data.csv',) as csvfile:file_list = csv.reader(csvfile,'mydialect')for line in file_list:data.append(line)
print(data)

如果文件是其他分隔符，如\n，则需要传入分隔符类型。

import csv data=[]
with open(r'data.csv',) as csvfile:file_list = csv.reader(csvfile,delimiter='\t')for line in file_list:data.append(line)
print(data)

读取

列表方式读取

import csvwith open('data.csv','r',encoding='utf-8') as csvfile:reader = csv.reader(csvfile)for row in reader:# 读取出的内容是列表格式的print(row,type(row),row[1])

字典方式读取

import csvwith open('data.csv','r',encoding='utf-8') as csvfile:reader = csv.DictReader(csvfile)for row in reader:# 读取的内容是字典格式的print(row['last_name'])

写入

列表方式写入

import csvwith open('data.csv','a+',encoding='utf-8',newline='') as csvfile:writer = csv.writer(csvfile)# 写入一行 writer.writerow(['1','2','3','4','5','5','6'])# 写入多行writer.writerows([[0, 1, 3], [1, 2, 3], [2, 3, 4]])

字典方式写入

import csv
with open('data.csv','a+',encoding='utf-8',newline='') as csvfile:filename = ['first_name','last_name']# 写入列标题writer = csv.DictWriter(csvfile,fieldnames=filename)writer.writeheader()writer.writerow({'first_name':'wl','last_name':'wtx'})writer.writerow({'first_name': 'Lovely', 'last_name': 'Spam'})writer.writerow({'first_name': 'Wonderful', 'last_name': 'Spam'})

json格式读写

python内置json包提供了四个函数：dumps、dump、loads、load。不带s的负责文件与字典的转换。带s的负责字符串和字典的转换。

字典到字符串 string json.dumps(dict)

import jsontest_str = json.dumps({'name' : "cat"})

字符串到字典 dict json.loads(string)

import jsontest_dict = json.loads("{'name' : "cat"}")

字典到json文件 json.dump(dict, file)

import jsonwith open("test.json","w") as f:json.dump({'name' : "cat"}, f)

json文件到字典 dict json.load(file)

import jsonwith open("test.json",'r') as f:test_dict = json.load(f)