How to read from one file and write it into another in Python
Python comes with the open() function to handle files. We can open the files in following modes:
read: Opens the file in reading mode.write: If the file is not present, it will create a file with the provided name and open the file in reading mode. It will overwrite the previous data.append: This is the same as opening in write mode but it doesn’t overwrite the previous data.
Reading line by line
-
Open the
file1, which has content in reading mode. -
Open the
file2in writing mode. -
Use
for inloop to go through every line infile1and write tofile2. -
Content is written to
file2. -
Close both the files.
-
We will check if the content is written into
file2or not by opening thefile2in reading mode and printing the content. -
Close the
file2.
Code
In the following code snippet, you can also check that file2.txt is created. Compare the list of before-after files in the output.
import os# print files in present dir before creating file2print("List of files before")print(os.listdir())print("\n")#open file1 in reading modefile1 = open('file1.txt', 'r')#open file2 in writing modefile2 = open('file2.txt','w')#read from file1 and write to file2for line in file1:file2.write(line)#close file1 and file2file1.close()file2.close()#open file2 in reading modefile2 = open('file2.txt','r')#print the file2 contentprint(file2.read())#close the file2file2.close()#print the files after creating file2, check the outputprint("\n")print("List of files after")print(os.listdir())print("\n")
Reading with read() method
It is the same as above except that we use read() method to read the content file1.
Check line 15, where we are reading the content from file1 with file1.read() and writing it to file2.
Code
import os# print files in present dir before creating file2print("List of files before")print(os.listdir())print("\n")#open file1 in reading modefile1 = open('file1.txt', 'r')#open file2 in writing modefile2 = open('file2.txt','w')#read from file1 and write to file2 using read methodfile2.write(file1.read())#close file1 and file2file1.close()file2.close()#open file2 in reading modefile2 = open('file2.txt','r')#print the file2 contentprint(file2.read())#close the file2file2.close()#print the files after creating file2, check the outputprint("\n")print("List of files after")print(os.listdir())print("\n")
We can open files with the with keyword, so we don’t need to close files.
import os# print files in present dir before creating file2print("List of files before")print(os.listdir())print("\n")#reading from file1 and writing to file2with open("file1.txt", "r") as file1:with open("file2.txt", "w") as file2:file2.write(file1.read())#reading from file1with open("file2.txt") as file2:print(file2.read())#print the files after creating file2, check the outputprint("\n")print("List of files after")print(os.listdir())print("\n")
