Reading and Writing lists to a file in Python
Last Updated :
01 Dec, 2023
Reading and writing files is an important functionality in every programming language. Almost every application involves writing and reading operations to and from a file. To enable the reading and writing of files programming languages provide File I/O libraries with inbuilt methods that allow the creation, updation as well and reading of data from the files. Python is no exception. Python too offers inbuilt methods to perform file operations. The io module in Python is used for file handling.
Reading and Writing Lists to a File in Python
The open(file path, mode) is used to open the required file in the desired mode. The open() method supports various modes of which three are of main concern:
- r:Â read (default)Python
- w: write
- a: append
write(): Insert the string str1 in a single line in the text file.
read(): used to read data from the file opened using the open() method.
Writing List to Files in Python
There are various methods for writing files in Python. Here, we will discuss some commonly used techniques.
- Using write()
- Using writelines()
- Using String Join Along with “with open” syntax
Writing List to Files in Python using write()
The file is opened with the open() method in w+ mode within the with block, the w+ argument will create a new text file in write mode with the help of write(). The with block ensures that once the entire block is executed the file is closed automatically.
Python3
l = ['Geeks','for','Geeks!']
with open('gfg.txt', 'w+') as f:
for items in l:
f.write('%s\n' %items)
print("File written successfully")
f.close()
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Output:
File written successfully
Here is the text file gfg.txt created:
Writing List to Files in Python using writelines()
The file is opened with the open() method in w mode within the with block, the argument will write text to an existing text file with the help of readlines(). The with block ensures that once the entire block is executed the file is closed automatically.
Python3
L = ["Geeks\n", "for\n", "Geeks\n"]
file1 = open('test1/myfile.txt', 'w')
file1.writelines(L)
file1.close()
|
Output:
Below is the text file gfg.txt:
Writing List to Files in Python using String Join Along with “with open” syntax
This Python code writes a list (`my_list`) to a file named “output.txt”. It uses the “with open” syntax for automatic file handling. The list elements are joined into a string with newline characters, and this string is written to the file. A confirmation message is printed.
Python3
my_list = ["item1", "item2", "item3", "item4"]
file_path = "main.txt"
with open(file_path, 'w') as file:
data_to_write = '\n'.join(my_list)
file.write(data_to_write)
print(f"The list has been written to {file_path}.")
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Output
Reading files in Python
There are various method to reading file in Python , here we used some generally used method for reading files in Python.
- using read()
- using readlines()
Read a file to a list in Python using read()
The file is opened using the open() method in reading r mode. The data read from the file is printed to the output screen using read() function. The file opened is closed using the close() method.
Python3
f = open('gfg.txt', 'r')
print(f.read())
f.close()
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Output :
Read a file to a list in Python using readlines()
The file is opened using the open() method in reading r mode. The data read from the file is printed to the output screen using readlines() function. The file opened is closed using the close() method.
Python3
f = open('gfg.txt', 'r')
for x in f.readlines():
print(x, end='')
f.close()
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Output:
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