File I/O and Modules in Python

Python tutorial · PySpark.in

File I/O (Input/Output) in Python means reading from and writing to files stored on your system.

It allows you to:

Python provides the built-in function open() to work with files.

1file_object = open(filename, mode)

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Mode	Description
'r'	Read (default). File must exist.
'w'	Write. Creates a new file or overwrites an existing one.
'a'	Append. Adds data at the end of the file.
'r+'	Read and write. File must exist.
'w+'	Write and read. Creates new file or overwrites.
'a+'	Append and read. Creates file if not exist.

# Open file in read mode
file = open("data.txt", "r")
# Read full content
content = file.read()
print(content)
# Close file
file.close()

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Note: Always close a file after using it to free up system resources.

Method	Description
file.read(size)	Reads specified number of bytes.
file.readline()	Reads one line at a time.
file.readlines()	Reads all lines and returns a list.

with open("output.txt", "w") as file:
 file.write("Hello, this is a new file!\n")
 file.write("Python makes file handling easy.")

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If the file exists, it will overwrite it.

1with open("output.txt", "a") as file:

2 file.write("\nThis line is added later.")

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This adds content at the end of the file without deleting previous data.

with open("data.txt", "r+") as file:
 content = file.read()
 print("Before writing:", content)
 file.write("\nNew line added!")

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