Editing Community Data Science Course (Spring 2015)/Day 1 Tutorial (section)

==Types==

[[File:Geometry.png|150px]]

There's a helpful '''function''' (more on what a function is in a second) called <code>type</code> that tells you what kind of thing -- what '''data type''' -- Python thinks something is. We can check for ourselves that Python considers '1' and '1.0' to be different data types:

 type(1)
 type(1.0)
 
So now we've seen two data types: '''integers''' and '''floats'''.

By the way, what is a "function"? Here are the important ideas about functions:

* A function encapsulates a useful bit of work and gives that work a name.
* You provide input to a function and it produces output. For example, the <code>type</code> function takes data as an input, and produces what type of data the data is (e.g. an integer or a float) as output.
* To use a function, write the name of the function, followed by an open parenthesis, then what the function needs as input (we call that input the '''arguments''' to the function), and then a close parenthesis.
* Programmers have a lot of slang around functions. They'll say that functions "take" arguments, or that they "give" or "pass" arguments to a function. "call" and "invoke" are both synonyms for using a function.

In the example above, "type" was the name of the function. <code>type</code> takes one argument; we first gave <code>type</code> an argument of 1 and then gave it an argument of 1.0.

==== Diagram of "calling" a function ====

[[File:Function_diagram.png]]

===Command history===

Stop here and try hitting the Up arrow on your keyboard a few times. The Python '''interpreter''' saves a history of what you've entered, so you can arrow up to old commands and hit Return to re-run them!