1.9 Turning Logic into Pseudocode Part 3 - IP
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>> Hello everyone and welcome back.
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This is Lesson 6 of intro to Python on
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cybrary on-demand and I am your instructor Joe Perry.
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In this video, we're going to cover
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the last objective of Lesson 6,
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and we're going to learn to use the Python help
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and their functions,
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and we're also going to take just a second to
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have a look at the Python documentation.
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To do this, we're going to
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work in our interpreter once again.
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Again, we're going to type Python
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3 at the command line,
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and we're going to open a Python 3 interpreter.
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The first function we're going to look at is help.
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Now, help as I said is a function which means that it
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is executed by putting the parentheses after it.
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We're not talking about functions very deeply yet,
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we'll do that in a later video.
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But once you run that command,
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it's going to open up
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this new subprogram that is
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the help program inside of the interpreter.
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You can see the instructions there.
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Give it the name of a module or a keyword,
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or basically any Python topic
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and if it has information about it,
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it will give you that information.
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Now, it can be a little bit tricky to use at time,
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just because for example, things like strings,
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which are very important components of Python,
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you don't actually find by writing the word strings,
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but it will try and give you information.
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For example, use help serve for help on the str class.
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It will try and give you information about how to search
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for whatever you're trying to get help on.
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Anyway, we're going to look at an example of this,
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which is just going to be the print function.
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You can see here, if you're familiar with the man pages,
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this is going to look pretty familiar to you.
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You've got your function at the top,
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and then after that you've got
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a description of how it's used,
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what arguments you would give it.
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Then you have an actual text description
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prints the values to
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a stream or to assist out standard out by default,
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sys.stdout is standard out,
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that just means print it to your screen.
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Which of course we've demonstrated
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even if we don't really know what functions are yet,
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we've demonstrated what print actually does.
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This is just giving us an explanation
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in a verbose way with more information about arguments.
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That's what help looks like,
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you can use help again for pretty much
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any module keyword or symbol if it has documentation,
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Python we'll be able to provide it.
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You leave that just by typing quit,
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now that's different from quitting your shell,
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which has done with quit with [NOISE] parentheses.
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In the help documentation,
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you just write the word quit.
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We've learned to use help.
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Now we're going to learn to use dir
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and dir is a tricky one to
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explain without a lot of knowledge of Python,
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because it deals with a topic called namespaces,
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and that's something we're not going to spend
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very much time on it all right now,
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other than to understand that a
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namespace basically just means
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the current environment in which you're executing code.
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It give you a better way of understanding
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that are more clear way,
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we're going to run dir right now without
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any other arguments or rather any information.
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This is a fresh shell,
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we haven't really done anything in it yet
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that would modify any information.
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You can see that we have these list
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of items with these underscores around them.
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Underscore is basically an indication in
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Python that those are internal functions,
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they're not really for use
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by the programmer or by other programs or other modules,
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those are built-in parts of your current namespace.
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Now, if you want to see how you can modify a namespace,
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a simple example would be creating a
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variable which we will call x,
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and another variable we will call y.
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Now, nothing has happened here because we
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were assigning to these variables.
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Even though we're in a REPL which
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generally reads, executes and prints,
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it's not going to print because it's sending
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that information to the variable instead.
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But we've got x equals one, y equals A.
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What we're going to do now, is we're going
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to rerun that dir command.
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You can see at the end of the list,
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these two new items have been included, x and y.
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Those are the variables we just created and that's what
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the namespace is and that's why I wanted to address it.
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What this is,
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is it's going to show you everything that is
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currently defined that you can have access to.
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Additionally, if you run it with command, for example,
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running it against one of those variables
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, not what I meant to do,
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[NOISE] you'll see a bunch more options.
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These are all of the things that are
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defined within the number variable.
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These are all of the functions,
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the methods that numbers have access to.
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To give an example of that, we can see x.numerator,
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which is actually not a method, it's an attribute.
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The numerator of course, of one is one,
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and we're going to go ahead and clear that screen.
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That's help and that's a dir.
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Those functions like I said or utility functions,
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not only will they become easier to
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understand as we go forward and videos,
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you're going to find more uses for them.
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You can do a bunch of stuff with both of those functions.
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I'll give you a ton of information.
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Oftentimes when you're trying to run down an error,
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those are the places to start because you'll be
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able to figure out what's happening with them.
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The last thing I want to show you here,
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and I think I might still have it up in my Browser,
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the Python 3 documentation.
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This is the https://docs.python.org or those backslashes,
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I can never remember which direction
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you call it a slash either way,
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docs.python.org, and then it's
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the Python 3.7.2 documentation specifically.
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You can see here this menu, you've got Python 3.8,
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which is still in debt for people
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who are using it ahead of time.
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3.6, 3.5, and 2.7.
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Now we're currently working in 3.6, but like I said,
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none of the coding we're going to be doing in this part
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of the class or in this class really in general,
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is going to run into any differences
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between 3.6 and 3.7,
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we're not going to worry about that.
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Between now and the intermediate in the advanced classes,
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we're going to move on to actually
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using the proper Python.
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Anyway, that's the Python help documentation,
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it shouldn't close that window,
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I'm not done with it at all.
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That's the Python help documentation
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you can see that they have tutorials,
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library references, language references.
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In fact, this tutorial I do want to draw
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attention to is absolutely spectacular.
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It's all part of the Python installed.
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It's all part of Python.
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It's free to use and free to read.
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I absolutely love it, and in fact,
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a lot of our material in this course is
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going to be based on information in that tutorial.
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In the intermediate and in the advance,
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we step away from what the tutorial covers.
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But in this intro course, you can absolutely use that,
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that's one of the best supplemental
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resources you can have access to.
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That's the end of this video,
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and therefore that's the end of Lesson 6.
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In Lesson 6 again,
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we discussed the Python syntax,
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how to use Python command line,
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how to create and execute Python scripts,
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and how to use the help and the dir functions.
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All of those things, again,
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are going to not only make more sense or become
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more relevant with each passing video,
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I just wanted you to be introduced to them now,
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so that we're ready to roll.
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Please join us in Lesson 7,
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where we're going to be discussing the Python data types.
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As always, I am your instructor Joe Perry,
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and thank you for watching this video intro to
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Python here on Cybrary on-demand.
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