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Q&A Why can't I use a library I just installed with Pip?

I tried installing package-installation-test[1] using Pip, and it appeared to be successful. But I can't use it as advertised, either by itself or by importing it from my code: Failed attempts ...

1 answer · posted 6mo ago by Karl Knechtel‭ · edited 6mo ago by Karl Knechtel‭

Question python installation runtime-environment pip

#2: Post edited by

Karl Knechtel‭ · 2024-06-16T13:59:35Z (6 months ago)
hide examples because they aren't strictly necessary to describe the problem; add some colour

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I tried installing [`package-installation-test`](https://pypi.org/project/package-installation-test/)[^1] using Pip, and it appeared to be successful. But I can't use it as advertised, either by itself or by importing it from my code:
```bash
$ pip install package-installation-test
Collecting package-installation-test
Using cached package_installation_test-1.0.0-py3-none-any.whl (3.1 kB)
Installing collected packages: package-installation-test
Successfully installed package-installation-test-1.0.0
$ demo-example-package
demo-example-package: command not found
$ python -m example_package
/path/to/python: No module named example_package
$ python -q
>>> import example_package
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'example_package'
>>>
```
Also, `demo-example-package` doesn't tab-complete in my shell.
According to the documentation, I should get results like this instead:
```bash
$ demo-example-package
Version 1.0.0 of example_package successfully installed.
The source code is in /path/to/example_package.
$ python -m example_package
Version 1.0.0 of example_package successfully installed.
The source code is in /path/to/example_package.
$ python -q
>>> import example_package # no error
>>> example_package.home()
PosixPath('/path/to/example_package')
```
Attempting to reinstall doesn't work either:
```
$ pip install package-installation-test
Requirement already satisfied: package-installation-test in /path/to/site-packages (1.0.0)
```
What gives?
[^1]: Full disclosure: I am the author of this package. I created it specifically to demonstrate the problem for the purpose of a canonical Q&A. Whatever package you're actually trying to install and use, the fundamentally problem is still the same.

I tried installing [`package-installation-test`](https://pypi.org/project/package-installation-test/)[^1] using Pip, and it appeared to be successful. But I can't use it as advertised, either by itself or by importing it from my code:
<details><summary>Failed attempts</summary>
<section class="notice is-danger">
```bash
$ pip install package-installation-test
Collecting package-installation-test
Using cached package_installation_test-1.0.0-py3-none-any.whl (3.1 kB)
Installing collected packages: package-installation-test
Successfully installed package-installation-test-1.0.0
$ demo-example-package
demo-example-package: command not found
$ python -m example_package
/path/to/python: No module named example_package
$ python -q
>>> import example_package
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'example_package'
>>>
```
</section></details>
Also, `demo-example-package` doesn't tab-complete in my shell.
According to the documentation, I should get results like this instead:
<details><summary>Expected results</summary>
<section class="notice is-success">
```bash
$ demo-example-package
Version 1.0.0 of example_package successfully installed.
The source code is in /path/to/example_package.
$ python -m example_package
Version 1.0.0 of example_package successfully installed.
The source code is in /path/to/example_package.
$ python -q
>>> import example_package # no error
>>> example_package.home()
PosixPath('/path/to/example_package')
```
</section></details>
Attempting to reinstall doesn't work either:
<section class="notice is-warning">
```
$ pip install package-installation-test
Requirement already satisfied: package-installation-test in /path/to/site-packages (1.0.0)
```
</section>
What gives?
[^1]: Full disclosure: I am the author of this package. I created it specifically to demonstrate the problem for the purpose of a canonical Q&A. Whatever package you're actually trying to install and use, the fundamentally problem is still the same.

#1: Initial revision by

Karl Knechtel‭ · 2024-06-16T13:19:01Z (6 months ago)

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Why can't I use a library I just installed with Pip?

I tried installing [`package-installation-test`](https://pypi.org/project/package-installation-test/)[^1] using Pip, and it appeared to be successful. But I can't use it as advertised, either by itself or by importing it from my code:
```bash
$ pip install package-installation-test
Collecting package-installation-test
  Using cached package_installation_test-1.0.0-py3-none-any.whl (3.1 kB)
Installing collected packages: package-installation-test
Successfully installed package-installation-test-1.0.0
$ demo-example-package
demo-example-package: command not found
$ python -m example_package
/path/to/python: No module named example_package
$ python -q
>>> import example_package
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'example_package'
>>> 
```
Also, `demo-example-package` doesn't tab-complete in my shell.

According to the documentation, I should get results like this instead:
```bash
$ demo-example-package 
Version 1.0.0 of example_package successfully installed.
The source code is in /path/to/example_package.
$ python -m example_package
Version 1.0.0 of example_package successfully installed.
The source code is in /path/to/example_package.
$ python -q
>>> import example_package # no error
>>> example_package.home()
PosixPath('/path/to/example_package')
```
Attempting to reinstall doesn't work either:
```
$ pip install package-installation-test
Requirement already satisfied: package-installation-test in /path/to/site-packages (1.0.0)
```
What gives?

[^1]: Full disclosure: I am the author of this package. I created it specifically to demonstrate the problem for the purpose of a canonical Q&A. Whatever package you're actually trying to install and use, the fundamentally problem is still the same.

python installation runtime-environment pip

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