cf-units

library3.3.1pypypi✓ verified 83d ago

A Python library for handling units of measure as required by the Climate and Forecast (CF) metadata conventions. It supports unit parsing, conversion, and computation, and is built on top of the UDUNITS-2 library. Current version is 3.3.1, with a stable release cadence.

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pip install cf-units

github ↗homepage ↗

INSTALL

IMPORT

SIG · CF-UNITS

cf-units

analyticspythonv3.3.1

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

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

Unit

✓ from cf_units import Unit

✗ import cf_units

Importing the package alone does not expose Unit directly; you must import the class.

date2num

✓ from cf_units import date2num

Common function for converting dates to numeric values.

Basic usage: create Unit objects and perform conversions.

from cf_units import Unit # Define units speed = Unit('m/s') temperature = Unit('celsius') # Convert value value_in_kmh = speed.convert(10.0, 'km/h') print(f'10 m/s in km/h: {value_in_kmh}') # Check compatibility print(speed.is_convertible(Unit('knots'))) # True

Debug

Known issues

breakingcf-units v3 requires Python >=3.11. Python 3.10 and older are not supported.

fix

Upgrade Python to 3.11+.

affects: >=3.0

gotchaThe underlying UDUNITS-2 library must be installed at the system level. pip install cf-units does not install it automatically.

fix

Install UDUNITS-2 via conda (conda install -c conda-forge udunits2) or your system package manager (e.g., apt-get install libudunits2-dev on Debian/Ubuntu).

affects: all

gotchaUnit strings are case-sensitive. For example, 'K' (kelvin) is different from 'k' (kilo prefix).

fix

Ensure unit strings follow UDUNITS-2 conventions; double-check case, especially for prefixes.

affects: all

Errors

Common errors & fixes

ModuleNotFoundError: No module named 'cf_units'

The package is installed as cf-units but imported as cf_units (with underscore).

fix

Use 'import cf_units' (underscore) in your code.

cf_units.external.ParserError: Can't parse unit string 'foo'

The unit string is invalid or not recognized by UDUNITS-2.

fix

Check the unit string for typos and ensure it adheres to UDUNITS definitions. Use cf_units.Unit.is_udunits() to validate.

OSError: Could not load UDUNITS library: 'libudunits2.so.0: cannot open shared object file: No such file or directory'

UDUNITS-2 shared library is not installed or not in the library path.

fix

Install UDUNITS-2 system-wide (e.g., conda install -c conda-forge udunits2 on Linux, or use conda environment).

Upgrade

Version history

3.3.1latest on PyPI · released Jan 16, 2026

Audit

Dependencies

udunits2requiredSystem library required for unit definitions and conversion; must be installed separately (e.g., via conda or system package manager).

Agent activity

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Resources

githubhttps://github.com/SciTools/cf-units ↗

homepagehttps://github.com/SciTools/cf-units ↗