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How to open a txt file in python

Jul 03, 2019 am 09:20 AM

How to open a txt file in python

Two ways to open files

f = open("data.txt","r")   #设置文件对象
f.close() #关闭文件


#为了方便,避免忘记close掉这个文件对象,可以用下面这种方式替代
with open('data.txt',"r") as f:    #设置文件对象
    str = f.read()    #可以是随便对文件的操作

Some simple operations on files:

1. Read files

1. Simply read the file into a string

f = open("data.txt","r")   #设置文件对象
str = f.read()     #将txt文件的所有内容读入到字符串str中
f.close()   #将文件关闭

2. Read the entire file line by line

#第一种方法
f = open("data.txt","r")   #设置文件对象
line = f.readline()
line = line[:-1]
while line:             #直到读取完文件
    line = f.readline()  #读取一行文件,包括换行符
    line = line[:-1]     #去掉换行符,也可以不去
f.close() #关闭文件


#第二种方法
data = []
for line in open("data.txt","r"): #设置文件对象并读取每一行文件
    data.append(line)               #将每一行文件加入到list中


#第三种方法
f = open("data.txt","r")   #设置文件对象
data = f.readlines()  #直接将文件中按行读到list里,效果与方法2一样
f.close()             #关闭文件

3. Read the file into an array

import numpy as np
data = np.loadtxt("data.txt")   #将文件中数据加载到data数组里

2 , write file

1. Simply write the string into txt

with open('data.txt','w') as f:    #设置文件对象
    f.write(str)                 #将字符串写入文件中

2. Write the list into the file

Single-layer list

data = ['a','b','c']
#单层列表写入文件
with open("data.txt","w") as f:
    f.writelines(data)

Double Layer list

#双层列表写入文件

#第一种方法,每一项用空格隔开,一个列表是一行写入文件
data =[ ['a','b','c'],['a','b','c'],['a','b','c']]
with open("data.txt","w") as f:                                                   #设置文件对象
    for i in data:                                                                 #对于双层列表中的数据
        i = str(i).strip('[').strip(']').replace(',','').replace('\'','')+'\n'  #将其中每一个列表规范化成字符串
        f.write(i)                                                                 #写入文件


#第二种方法,直接将每一项都写入文件
data =[ ['a','b','c'],['a','b','c'],['a','b','c']]
with open("data.txt","w") as f:                                                   #设置文件对象
    for i in data:                                                                 #对于双层列表中的数据
        f.writelines(i)                                                            #写入文件

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