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Using your environment

Installing sndfile from PyPi

Let's try to install sndfile from PyPi again, this time in the activated Spack environment. The advantage we have here specifically with Python is that we don’t need an additional Python virtualenv. Any pip install commands will install Python libraries inside the Spack environment:

pip install output 
[spack-python] $ pip install sndfile
Collecting sndfile
  Using cached sndfile-0.2.0.tar.gz (4.3 kB)
  Installing build dependencies ... done
  Getting requirements to build wheel ... done
  Installing backend dependencies ... done
  Preparing metadata (pyproject.toml) ... done
Collecting cffi>=1.0.0 (from sndfile)
  Using cached cffi-1.17.1-cp312-cp312-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (479 kB)
Collecting pycparser (from cffi>=1.0.0->sndfile)
  Using cached pycparser-2.22-py3-none-any.whl (117 kB)
Building wheels for collected packages: sndfile
  Building wheel for sndfile (pyproject.toml) ... done
  Created wheel for sndfile: filename=sndfile-0.2.0-cp312-cp312-linux_x86_64.whl size=29722 sha256=95ee841571f4befe79b8ac2aca07787b147c82fcd433bcd981d9af88ab567fa3
  Stored in directory: /data/scratch/abc123/.cache/pip/wheels/3c/ce/44/b9c297d8a032a4f7ff6eefb880458d397d66e14b94d600d3bd
Successfully built sndfile
Installing collected packages: pycparser, cffi, sndfile
Successfully installed cffi-1.17.1 pycparser-2.22 sndfile-0.2.0

[spack-python] $ ls -1 /data/scratch/abc123/spack-environments/spack-python/.spack-env/view/lib/python3.12/site-packages
cffi
cffi-1.17.1.dist-info
_cffi_backend.cpython-312-x86_64-linux-gnu.so
pip
pip-23.1.2.dist-info
pycparser
pycparser-2.22.dist-info
README.txt
sndfile
sndfile-0.2.0.dist-info

Success! And indeed, we are able to import the sndfile library in an interactive Python shell inside the activated Spack environment:

Using sndfile in a Python shell 
[spack-python] $ python
Python 3.12.1 (main, Jun  6 2024, 15:45:45) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import sndfile
>>> import pathlib
>>> SAMPLES = pathlib.Path("/data/scratch/abc123/audio")
>>> with sndfile.open(SAMPLES / "sample.wav", "r") as sample:
...   print("frames: {}".format(sample.frames))
...   print("format: major={0[0]}, minor={0[1]}".format(sample.format))
...   print("samplerate: {}".format(sample.samplerate))
...   print("channels: {}".format(sample.channels))
...   print("sections: {}".format(sample.sections))
...
frames: 698194
format: major=wav, minor=default
samplerate: 44100
channels: 2
sections: 1
>>>

In a job script or interactive job

Now that your environment is created, you can activate it and use it in a job script or interactive job with the following lines:

module load spack/<version>
spack env activate /data/scratch/abc123/spack-environments/spack-python
python script.py

The -p flag is not required in job scripts because the decorated prompt will not be observed within non-interactive jobs. The sndfile Python library should be available for any Python scripts you run as long as you activate your Spack environment as part of the job script or during the interactive job.