Simple pure-python module for reading and writing nrrd files.
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pynrrd is a pure-Python module for reading and writing NRRD files into and from numpy arrays.


The module's only dependency is numpy.


Install via pip and PyPi repository (recommended)

pip install pynrrd

Install via pip and GitHub

pip install git+

Install from source (recommended for contributing to pynrrd)

For developers that want to contribute to pynrrd, you can clone the pynrrd repository and install it using the following commands:

git clone
cd pynrrd
pip install .

or, for the last line, instead use:

pip install -e .

to install in 'develop' or 'editable' mode, where changes can be made to the local working code and Python will use the updated pynrrd code.

Example usage

import numpy as np
import nrrd

# Some sample numpy data
data = np.zeros((5,4,3,2))
filename = 'testdata.nrrd'

# Write to a NRRD file
nrrd.write(filename, data)

# Read the data back from file
readdata, header =


Run the following command in the base directory to run the tests:

python -m unittest discover -v nrrd/tests

Next Steps

For more information, see the documentation.


See the LICENSE for more information.