Repository: pykeen/pykeen
Issue: AttributeError: module 'matplotlib' has no attribute 'get_data_path' when running result.plot()
Root cause: Environment Incompatibility

**Describe the bug**
Hi, I followed the [toy example guide](https://pykeen.readthedocs.io/en/stable/tutorial/translational_toy_example.html) and the training was fine, but when running result.polt(), AttributeError: module 'matplotlib' has no attribute 'get_data_path'  occured. 

```
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-15-736ea0a001aa> in <module>
     16 )
     17 
---> 18 result.plot()

C:\anaconda3\lib\site-packages\pykeen\pipeline\api.py in plot(self, **kwargs)
    318         """
    319         from .plot_utils import plot
--> 320         return plot(self, **kwargs)
    321 
    322     def save_model(self, path: Union[str, pathlib.Path]) -> None:

C:\anaconda3\lib\site-packages\pykeen\pipeline\plot_utils.py in plot(pipeline_result, er_kwargs, figsize)
    267 def plot(pipeline_result, er_kwargs: Optional[Mapping[str, str]] = None, figsize=(10, 4)):
    268     """Plot all plots."""
--> 269     import matplotlib.pyplot as plt
    270 
    271     fig, axes = plt.subplots(1, 2, figsize=figsize)

C:\anaconda3\lib\site-packages\matplotlib-3.4.2-py3.8-win-amd64.egg\matplotlib\__init__.py in <module>
    821 # triggering resolution of _auto_backend_sentinel.
    822 rcParamsDefault = _rc_params_in_file(
--> 823     cbook._get_data_path("matplotlibrc"),
    824     # Strip leading comment.
    825     transform=lambda line: line[1:] if line.startswith("#") else line,

C:\anaconda3\lib\site-packages\matplotlib-3.4.2-py3.8-win-amd64.egg\matplotlib\cbook\__init__.py in _get_data_path(*args)
    532     ``*args`` specify a path relative to the base data path.
    533     """
--> 534     return Path(matplotlib.get_data_path(), *args)
    535 
    536 

AttributeError: module 'matplotlib' has no attribute 'get_data_path'
```

**To Reproduce**
```
from pykeen.pipeline import pipeline
DATA_PATH = "C:/Users/Hao Liu/Desktop/data.txt"
tf = TriplesFactory.from_path(DATA_PATH)
training, testing = tf.split()
results = pipeline(
    training=training,
    testing=testing,
    model = 'TransE',
    model_kwargs=dict(embedding_dim=2),
    random_seed=1,
    device='cpu',
)
results.plot()
```

**Expected behavior**
Plot the figures like the [toy example guide](https://pykeen.readthedocs.io/en/stable/tutorial/translational_toy_example.html)  shows.

**Environment:**
 Key             | Value                    |
|-----------------|--------------------------|
| OS              | nt                       |
| Platform        | Windows                  |
| Release         | 10                       |
| User            | *****                  |
| Time            | Wed Jun 23 09:26:20 2021 |
| Python          | 3.8.3                    |
| PyKEEN          | 1.5.1-dev                |
| PyKEEN Hash     | UNHASHED                 |
| PyKEEN Branch   |                          |
| PyTorch         | 1.7.0+cpu                |
| CUDA Available? | false                    |
| CUDA Version    | N/A                      |
| cuDNN Version   | N/A                      |


**Additional information**
The matplotlib is the up-to-date version.
`(base) C:\Users\Hao Liu>pip install --upgrade matplotlib

Requirement already up-to-date: matplotlib in c:\anaconda3\lib\site-packages\matplotlib-3.4.2-py3.8-win-amd64.egg (3.4.2)
Requirement already satisfied, skipping upgrade: cycler>=0.10 in c:\anaconda3\lib\site-packages (from matplotlib) (0.10.0)
Requirement already satisfied, skipping upgrade: kiwisolver>=1.0.1 in c:\anaconda3\lib\site-packages (from matplotlib) (1.3.1)
Requirement already satisfied, skipping upgrade: numpy>=1.16 in c:\anaconda3\lib\site-packages (from matplotlib) (1.19.1)
Requirement already satisfied, skipping upgrade: pillow>=6.2.0 in c:\anaconda3\lib\site-packages (from matplotlib) (7.2.0)
Requirement already satisfied, skipping upgrade: pyparsing>=2.2.1 in c:\anaconda3\lib\site-packages (from matplotlib) (2.4.7)
Requirement already satisfied, skipping upgrade: python-dateutil>=2.7 in c:\anaconda3\lib\site-packages (from matplotlib) (2.8.1)
Requirement already satisfied, skipping upgrade: six in c:\anaconda3\lib\site-packages (from cycler>=0.10->matplotlib) (1.15.0)`


Hi @Hao-666 ,

this sounds like a problem with the `matplotlib` installation. [Here](https://stackoverflow.com/a/53936824) a similar issue is described where the are two versions of `matplotlib` installed, one in `conda`, and one in `pip`.

Can you check if `conda` also has a matplotlib installation?

```
conda list matplotlib
```



> Hi @Hao-666 ,
> 
> this sounds like a problem with the `matplotlib` installation. [Here](https://stackoverflow.com/a/53936824) a similar issue is described where the are two versions of `matplotlib` installed, one in `conda`, and one in `pip`.
> 
> Can you check if `conda` also has a matplotlib installation?
> 
> ```
> conda list matplotlib
> ```

Hi @mberr ,

Thanks for this information. Probably that's the reason. Sorry I don't have the chance to check now... I re-installed the whole anaconda due to other reasons and now when I run the codes again it is fine. 

After install or reinstall matplotlib, python kernel need restart.