Add materials for Numpy Tutorial article.

[rpalo]

Where to put new files:

• New files should go into a top-level subfolder, named after the article slug. For example: my-awesome-article

How to merge your changes:

1. Make sure the CI code style tests all pass (+ run the automatic code formatter if necessary).
2. Find an RP Team member on Slack and ask them to review & approve your PR.
3. Once the PR has one positive ("approved") review, GitHub lets you merge the PR.
4. 🎉

[rpalo]

Hm. Following the steps exactly in the CircleCI build/install/lint process on my machine gives no issues for Black.

Not sure how to proceed.

[dbader]

Hmm, any chance you're on a different version of black locally than what we use on the repo?

Here's the requirements file we're using on CI:

https://github.com/realpython/materials/blob/master/requirements.txt#L1-L2

[bzaczynski]

@rpalo Yeah, it's a version issue. When I used the latest black, it didn't report any problems with those source files. However, after installing the one from the materials' requirements, it did complain about one file.

In this case, I'd argue that it makes sense to keep Ryan's original formatting. @dbader Is there a way to suppress a rule in black in an unobtrusive way? Alternatively, can we update the black version here?

$ black --version
black, version 20.8b1
$ black . --diff
All done! ✨ 🍰 ✨
5 files would be left unchanged.

$ black --version
black, version 19.10b0
$ black . --diff
--- durer.py    2020-10-22 10:34:18.389230 +0000
+++ durer.py    2020-10-22 10:39:17.843831 +0000
@@ -1,16 +1,11 @@
 """Validating Dürer's magic square."""
 
 import numpy as np
 
 square = np.array(
-    [
-        [16, 3, 2, 13],
-        [5, 10, 11, 8],
-        [9, 6, 7, 12],
-        [4, 15, 14, 1],
-    ]
+    [[16, 3, 2, 13], [5, 10, 11, 8], [9, 6, 7, 12], [4, 15, 14, 1],]
 )
 
 for i in range(4):
     assert square[i, :].sum() == 34
     assert square[:, i].sum() == 34
reformatted durer.py
All done! ✨ 🍰 ✨
1 file reformatted, 4 files left unchanged.

[bzaczynski]

🔗 Link

Can you please include a link to the original article? Ideally, the link should spell the title:

Suggested change

	# Code Materials for the Numpy Tutorial
	These are code resources for the Numpy Tutorial article by @rpalo.
	# NumPy Tutorial: First Steps in Data Science
	This folder contains the sample code for the [NumPy Tutorial](https://realpython.com/numpy-tutorial/) by @rpalo.

[bzaczynski]

🤝 Handholding

I would also recommend showing the reader how to use those examples. For instance, show a command that installs NumPy and Matplotlib, which then could be quickly copied-and-pasted in the terminal:

$ python -m pip install numpy matplotlib

Better yet, add a requirements.txt file with all the dependencies with tested versions, and show how to use it:

$ python -m pip install -r requirements.txt

Show how to run the individual scripts and their outputs:

$ python normal.py
[-0.34057664  0.03159261 -0.46815197 -0.30809633 -0.37834691]
9534
10000
0.9534

[bzaczynski]

⚠️ Wrong Filename

Suggested change

	img = mpimg.imread("kitten.png")
	img = mpimg.imread("kitty.jpg")

[bzaczynski]

🎩 Style Tip

Use consistent code formatting. Some of your files follow PEP 8 with respect to the number of blank lines, while others don't, for example.

[bzaczynski]

👩‍💻 Technical Recommendation

Since you're showing output in most of your Python source files, maybe it would make sense to replace them with Jupyter Notebooks (.ipynb files)? They allow to save the expected output with them. What do you think?

(You can take a look at build-a-web-scraper/ folder, which comes with a few of those notebooks.)

[dbader]

FYI I bumped flake8 and black on master and that resolved the linter complaints on this PR :)

[rpalo]

Woohoo! Thanks. I'm planning on resolving all of the other requests (along with the requests on the article draft) today or tomorrow.

Thanks again 😄

[bzaczynski]

@rpalo I just noticed a typo in the Maclauren name. It's actually Maclaurin with an "i" after Colin Maclaurin. Please update the relevant notebook as well as the file name. Thanks!

[bzaczynski]

lgtm

[rpalo]

Note, no changes to the code or anywhere else in the repo. Just re-running the image_mod.ipynb with higher res kitty images to match the images I'm using in the article to appease the preflight.