Installing additional python packages

· ☕ 4 min read · ✍️ Joe

iolite comes with many useful python packages, but we cannot anticipate everything our users might want to use python for in iolite. If your great idea depends on additional python packages that we do not include, here is a quick overview of one way you can install those packages.

Typically the Python Package Index is the best place to start if you know which package you’re looking for. You would start by searching for the package, clicking the Download files link on the left side under Navigation and downloading the appropriate file for your operating system and python version.

This is where we encounter the first possible complication. Python packages that are pure python (no machine/operating system specific code) are easy and will normally be provided as a single .whl or zip file. Python packages that are not pure python are a bit tricker and require you to know which version of python you are using (version 3.6 is embedded in iolite at the time of writing but may change in the future) and which operating system / architecture you are using. As an example for the latter scenario, let’s look at the files available for SciPy. The format generally looks like:


Where VERSION is the package version (1.4.1 as I write this), PYTHONVERSION is 36 and the OSINFO might be something like win_amd64 or macosx_10_6_intel. So, for this particular example, the files we would want to download would be scipy-1.4.1-cp36-cp36m-win_amd64.whl for PC and scipy-1.4.1-cp36-cp36m-macosx_10_6_intel.whl for Mac.

Note that this technique does not do any dependency resolution. For example, if package A depends on package B and you’ve installed A as above, you will also need to install package B.

An example

As an example, let’s install SymPy, a symbolic mathematics package. When we search the Python Package Index and go to the SymPy download files there are two versions: a .whl file and a .tar.gz. A .whl file is a python package format that is essentially a zip file and the .tar.gz is a also a compressed archive, but one not commonly used on Macs and PCs. If we download the .whl version, we could simply rename it to .zip, extract it and copy it to our python site-packages. The location of your site-packages can be found in iolite’s preferences. However, do note that you can also add a location outside of the application installation directory if you do not want these packages replaced every time you update iolite.

Alternatively, a simple python script runnable from the python workspace can be used to install .whl files:

from iolite.QtGui import QFileDialog, QMessageBox
import zipfile
import sys

whl_file = QFileDialog.getOpenFileName()
site_path = [p for p in sys.path if 'site-packages' in p][0]

button = QMessageBox.question(None, 'Install Wheel', 'Are you sure you want to install:\n%s\nto\n%s?'%(whl_file, site_path))

if button == QMessageBox.Yes:
	with zipfile.ZipFile(whl_file, 'r') as zip_ref:

	QMessageBox.information(None, 'Install Wheel', 'You will need to restart iolite before you can use the new package')

Now if you try to import the sympy package in iolite, for example:

from sympy import *
# or
from sympy import expr

you will likely see an error as follows:

ModuleNotFoundError: No module named ‘mpmath’

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File “”, line 1, in
File “/Applications/”, line 21, in
raise ImportError(“SymPy now depends on mpmath as an external library. "
ImportError: SymPy now depends on mpmath as an external library. See for more information.

If you examine the error message, you’ll see that sympy also depends on a package called mpmath. We can again use the Python Package Index to find and download mpmath. In this case, they only provide a .tar.gz, so you would need to find a way to extract that on your operating system. Since the archive is not in the .whl format, we cannot simply copy the whole thing into our site-packages. However, by inspecting the contents, it is apparent that this is again a pure python package and we can copy the mpmath folder within the archive to iolite’s site-packages path.

Once that is complete, we can check that sympy is working via iolite’s console (or workspace):

from sympy import *
x = Symbol('x')
print(integrate(1/x, x))
# outputs log(x)

And that is it! If you have any questions or if you are having a hard time installing a package, please send us an email.

Click here to discuss.

iolite team
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