added Classes and Objects callout

[mpaegert]

Adding "Classes and Objects Callout to Episode 1

After the first "type" command I added a short callout "Classes and Objects". All "type" outputs will start with "" and there is no mentioning anywhere what a "class" is. Added a class entry to the reference as well. This may make the the episode about 1 to 2 minutes longer.

Please note: this is part of my checkout procedure.

[mpaegert]

Seems all commits are automatically part of a pull request, I can not create them episode by episode. I leave changes to episode 2 in for now and do not commit changes to Episodes 7 and 10.

Please note that this is part of my checkout procedure. I want to get it right, so please advise how to proceed with the remaining changes.

Episode 2

Loading the data into variable "data", then printing it. This saves tile to repeat numpy.loadtxt later on.

Added sneak peek to episode 3 by letting matplotlib plot the data in order to get an overview. This should illustrate the power of the library concept and motivate for the rather dry part about indexing and slicing following it.

Together with the introduction of class in episode 1, students now better understand the output of "print(type)data))" - .

Slicing: added not "row index comes first". This is not clearly stated anywhere else.

Adding a clarifying note about "axis = 0" and "axis = 1" after fig/python-operations-across-axes.png.

These changes do not make the episode longer.

[maxim-belkin]

Hi, Martin! Thank you for the pull request!

Seems all commits are automatically part of a pull request, I can not create them episode by episode. I leave changes to episode 2 in for now and do not commit changes to Episodes 7 and 10.

You have to use Git branches to submit unrelated changes. I see you submitted this PR from the gh-pages branch of your fork. Usually, it is recommended to submit PRs from a different branch of your fork, because later down the road you will want to keep the gh-pages branch in your fork in sync with that in the main lesson. If desired, so you can follow these instructions to restore the state of your gh-pages branch and submit a new PR from a different branch.

After the first "type" command I added a short callout "Classes and Objects".

I think that explaining why Python says class when we execute type(something) is a good idea. At the same time, it is too early (in the lesson and for those new to programming) to discuss classes in detail. I'd like to suggest to limit the discussion to saying that everything in Python is an object of a certain "class" and that type reports the class of an object.

We can discuss other (proposed) changes in other PRs when you submit them.

Thanks for your contribution and welcome to The Carpentries, @mpaegert!