Editing Community Data Science Course (Spring 2019)/Day 2 Lecture (section)

=== Review Week 1 python material ===

* math: using python as a calculator
**addition, subtraction, multiplication, division
**division shows something different: <code>8/2</code> versus <code>2*2</code>
* <tt>type()</tt>
** there are different types of things in python (called objects)
** variables that "know about the decimal place" (int) and variables that don't (floats)
** variables that are strings.
* variables
** assignment of variables
** e.g., math with variables: scale up a recipe, into an assignment
** you can assign to a variable and it will replace the old value
* strings
** things within quotation marks
** adding strings with "concatenation" (smushing things together)
** e.g., <code>print("Hello" + name)</code>
** concatenating strings and integers doesn't work (e.g., <code>print(1 + "tommy")</code>)
** 1 is different than "1"; name is different than "name"
** convert "1" to 1 with the <code>int()</code> function
** single quotes versus double quotes (python doesn't care)
** you can also multiply strings! (although it's not clear why you want to)
** '''The type of a variable tells you what you can do with it'''
* Booleans
** comparisons (e.g., <code>1 == 1</code> or <code>1 == 0</code>)
*** you can compare strings (case sensitive!)
*** also >, <, and !=
** type() shows that the output of True or False is <code>bool</code>
** e.g., <code>"i" in "team"</code>
** e.g., <code>"i" not in "team"</code>
* <tt>if</tt>/<tt>elif</tt>/<tt>else</tt> ('''move to external file''')
** if, something that evaluates to a Boolean, and then colon
** e.g., <code>if "tom" in "tommyguy"</code>
** e.g., adding else example: <code>if brother_age > sister_age</code>
** e.g., temperature range
** e.g., adding elif: fix the bug in the previous program if they were the same age
** indent with spaces (we use 4 spaces!)