memoryview() Built-in Function
Python - memoryview()
Python memoryview() built-in function is used to get the memory view object that allows you to view the contents of a bytes-like object as a sequence of machine values.
memoryview() built-in function can be used for efficient data manipulation, sharing memory between objects, interacting with C code, etc.
In this tutorial, you will learn the syntax and usage of memoryview() built-in function, and cover some examples.
Syntax
The syntax of memoryview() function is
memoryview(object)where
| Parameter | Description |
|---|---|
object | A bytes-like object. e.g., bytes, bytearray, or another memory view object. |
Examples
1. Get memory view of bytes object
In the following program, we take a bytes object, and get a memoryview object for this bytes object.
Python Program
data = bytearray(b'hello world')
# Get memory view of data
mv = memoryview(data)
print(mv)Output
<memory at 0x104725d80>2. Slice memoryview
memoryview supports slicing. In the following program, we slice the memoryview object, and print it to standard output.
Python Program
data = bytearray(b'hello world')
# Get memory view of data
mv = memoryview(data)
# Slice memoryview
mvslice = mv[2:8]
print(bytes(mvslice))Output
b'llo wo'Uses of memoryview()
memoryview() built-in function can be used for the following purposes.
- Efficient data manipulation: By using
memoryview()on a bytes-like object, you can efficiently manipulate the data as a sequence of machine values. This can be faster than copying the data into a new object or converting it to a different data type. - Sharing memory between objects: Since
memoryview()returns a view of the data rather than a new object, it can be used to share memory between different parts of your code. For example, you could create a memory view of a large bytes-like object and pass it to a function that only needs to access a small portion of the data. - Interacting with C code: The
memoryview()function can be useful when interacting with C code that operates on raw memory. You can pass a memory view object to a C function that expects a pointer to memory, allowing you to access and manipulate the data in Python and C code.
Summary
In this Built-in Functions tutorial, we learned the syntax of the memoryview() built-in function, and how to use this function to create a memoryview for a bytes-like object.