affine

library3.0.0pypypi✓ verified 24d ago

Affine is a Python library providing matrices that describe two-dimensional affine transformations of the plane. It is commonly used in geospatial contexts, such as with raster data, to transform between image and world coordinates. The current stable version is 2.4.0, with a major rewrite for version 3.0 currently in release candidate stages.

data serialization

pip install affine

github ↗package ↗

INSTALL

IMPORT

SIG · AFFINE

affine

datapythonv3.0.0

Install

1.6s avg

Import

96ms

Disk

16MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v3.0.0 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.910 runs

installs and imports cleanly · install 0.0s · import 0.101s · 18.4MB

glibc

py 3.10–3.910 runs

installs and imports cleanly · install 1.6s · import 0.091s · 19MB

16MB installed

● package 16MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

Affine

✓ from affine import Affine

Demonstrates creating identity, translation, scaling, and rotation affine objects, combining them, and applying them to a point.

from affine import Affine # Create an identity affine transform identity = Affine.identity() print(f"Identity: {identity}") # Create a translation transform (move by 10 units in x, 20 in y) translation = Affine.translation(10, 20) print(f"Translation: {translation}") # Create a scaling transform (scale by 2x) scaling = Affine.scale(2.0) print(f"Scaling: {scaling}") # Combine transforms by multiplication (scaling then translation) combined = translation * scaling print(f"Combined (scale then translate): {combined}") # Apply the combined transform to a point (0, 0) x, y = 0, 0 x_prime, y_prime = combined * (x, y) print(f"Original point ({x}, {y}) transformed to ({x_prime}, {y_prime})") # Example of rotation (rotate by 45 degrees) rotation = Affine.rotation(45.0) print(f"Rotation 45 deg: {rotation}") # Apply rotation to a point (1, 0) x_rot, y_rot = rotation * (1, 0) print(f"Point (1,0) rotated 45 deg: ({x_rot:.2f}, {y_rot:.2f})")

Debug

Known issues

breakingIn `affine` 3.0 (alpha/beta/rc releases), the `Affine` class is no longer a named tuple. This means direct JSON serialization without a custom adapter will break, and any code relying on `namedtuple` specific behaviors will need adjustment.

fix

Update code to treat `Affine` as a regular class instance. For JSON serialization, implement a custom adapter (e.g., by converting to a list or dictionary) or serialize its `to_coeffs()` output.

affects: >=3.0a1

breakingThe precision for properties like `is_conformal` has changed from a global module attribute to an `Affine` class or instance attribute in version 3.0. Additionally, the `is_degenerate` property is now exact, removing previous precision considerations.

fix

Access precision settings via `Affine` class or instance attributes. Adjust code that relied on a global `precision` value or the non-exact `is_degenerate` behavior.

affects: >=3.0a1

breakingThe sense of rotation has been reversed in `affine` 3.0. A positive angle now rotates a point counter-clockwise about the pivot point, which might be a change from previous versions' behavior.

fix

Review and update rotation angle values if your application relies on a specific direction of rotation for positive angles.

affects: >=3.0a1

breakingFor `affine` 3.0 and later, Python 3.9 or newer is required. Previous versions (like 2.4.0) supported Python 3.7+.

fix

Ensure your environment uses Python 3.9 or a newer compatible version before upgrading to `affine` 3.0.

affects: >=3.0a1

gotchaWhen working with geospatial raster data, it's crucial to remember that the `affine` library (like GDAL and Rasterio) typically uses an origin (0,0) at the upper-left corner of the image, with Y increasing downwards. This differs from a standard Cartesian coordinate system where Y typically increases upwards.

fix

Always consider the coordinate system conventions (e.g., 'pixel corner' vs 'pixel center', Y-axis direction) when applying or interpreting affine transforms for geospatial data. Tools like `Affine.from_gdal()` can help convert standard GDAL geotransforms.

affects: All versions

Errors

Common errors & fixes

ModuleNotFoundError: No module named 'affine'

The 'affine' library is not installed in the Python environment.

fix

Install the 'affine' library using pip: 'pip install affine'.

ImportError: cannot import name 'Affine' from 'affine'

The 'Affine' class is not directly accessible from the 'affine' module.

fix

Import the 'Affine' class correctly: 'from affine import Affine'.

TypeError: 'Affine' object does not support item assignment

Attempting to modify an immutable 'Affine' object directly.

fix

Create a new 'Affine' object with the desired modifications instead of modifying the existing one.

AttributeError: 'DatasetReader' object has no attribute 'affine'.

When working with `rasterio` datasets, the affine transformation matrix is accessed via the `.transform` attribute, not the deprecated `.affine` attribute.

fix

Use `raster.transform` instead of `raster.affine`. For example, if `raster = rasterio.open(...)`, use `affine_transform = raster.transform`.

ModuleNotFoundError: No module named 'affine'.

The `affine` Python package is not installed in your current Python environment.

fix

Install the package using pip: `pip install affine`.

Upgrade

Version history

3.0.0latest on PyPI · released Aug 8, 2026

Audit

Dependencies

No dependency data recorded yet.

Agent activity

70 hits · last 30 days

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Amazon

OpenAI (training)

Resources

githubhttps://github.com/rasterio/affine ↗

packagehttps://pypi.org/project/affine/ ↗