cdflib

library1.3.12pypypi✓ verified 85d ago

A Python library for reading and writing NASA Common Data Format (CDF) files. Current version 1.3.10, released 2025-05. Maintained by LASP, supports Python >=3.9. Includes integration with xarray and handles ISTP compliance checks.

data serialization

pip install cdflib

github ↗package ↗

INSTALL

IMPORT

SIG · CDFLIB

cdflib

datapythonv1.3.12

Install

3.6s avg

Import

383ms

Disk

90MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v1.3.12 · 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 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 0.380s · 90MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 3.6s · import 0.386s · 86MB

90MB installed

● package 90MB

Code

Verified usage

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

CDF

✓ from cdflib import CDF

✗ from cdflib.cdf import CDF

CDF is a top-level class in cdflib, not a submodule.

cdf_to_xarray

✓ from cdflib import cdf_to_xarray

✗ from cdflib.xarray import cdf_to_xarray

cdf_to_xarray is a top-level function, not nested in an xarray submodule.

xarray_to_cdf

✓ from cdflib import xarray_to_cdf

✗ from cdflib.xarray import xarray_to_cdf

Same as cdf_to_xarray; both are top-level functions.

Open a CDF file, read global attributes, list variables, and read data for a variable.

from cdflib import CDF cdf_file = CDF('example.cdf') info = cdf_file.globalattsget() print(info) vars = cdf_file.cdf_info() print(vars) data = cdf_file.varget('variable_name') print(data.shape) cdf_file.close()

Debug

Known issues

breakingIn version 1.3.3, the deprecated functions `from_unixtime`, `from_datetime`, `unixtime_to_cdftt2000`, `datetime_to_cdftt2000`, and `datetime64_to_cdftt2000` were fully removed. Use `CDFtime` class or `astropy.time.Time` conversion instead.

fix

Replace `from cdflib.util import from_unixtime` with `CDFtime(utc).tt2000` or use astropy.

affects: >=1.3.3

gotchaWhen using `cdf_to_xarray`, `DELTA_VAR` variables are no longer promoted to coordinates (since 1.3.5). If you rely on them as coordinates, you must manually add them via xarray.

fix

After calling `cdf_to_xarray`, do `ds = ds.assign_coords(delta_var=ds['delta_var'])` if needed.

affects: >=1.3.5

gotchaThe CDF class is not thread-safe. Do not share a CDF object across threads; open separate instances per thread.

fix

Use a new CDF instance per thread (or use read locks).

affects: all

deprecatedAs of version 1.3.10, `CDF.varget()` with `start` and `count` parameters uses 0-based indexing. Some users mistakenly use 1-based indexing from IDL/old CDF standards.

fix

Always use 0-based indices: `cdf.varget('var', start=[0], count=[10])`.

affects: >=1.0.0

Errors

Common errors & fixes

ModuleNotFoundError: No module named 'cdflib.cdf'

Incorrect import path; CDF is a class in the top-level cdflib package, not a submodule.

fix

Use `from cdflib import CDF` instead.

AttributeError: module 'cdflib' has no attribute 'cdf_to_xarray'

Attempting to import cdf_to_xarray from a wrong location or missing install (e.g., without xarray dependency).

fix

Install xarray (`pip install xarray`) and import using `from cdflib import cdf_to_xarray`.

TypeError: 'numpy.float64' object cannot be interpreted as an integer

Passing a numpy float as start/count index to varget(). varget() expects Python ints.

fix

Cast to int: `start=int(start_val)` or use `varget('var', start=[int(s) for s in start])`.

Upgrade

Version history

1.3.12latest on PyPI · released Jun 1, 2026

Audit

Dependencies

numpyrequiredcore dependency for array operations and CDF data type conversion

astropyoptionaloptional, used for time conversions and FITS compatibility

xarrayoptionaloptional, used for xarray integration (cdf_to_xarray, xarray_to_cdf)

Agent activity

16 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/lasp/cdflib ↗

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