Community Data Science Workshops (Fall 2014)/Day 1 lecture

Welcome to the Saturday lecture section of the Community Data Science Workshop! For about 2 hours, we'll work through an introduction to the Python programming language via both a lecture and hand-on exercises.

Resources

• Python data types cheat sheet
• Python loops cheat sheet
• state_capitals.py -- the state capitals example.

Lecture outline

Review Friday material

• math: using python as a calculator
  • addition, subtraction, multiplication, division
  • division shows something different: 8/2 versus 1/2
• type()
  • 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
  • assignment of variaibles
  • 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 "concatination" (smushing things together)
  • e.g., print("Hello" + name)
  • concatenating strings and integers don't work (e.g., print(1 + "mako"))
  • 1 is different than "1"; name is different than "name"
  • single quotes versus double quotes (python doesn't care)
  • you can also multiply strings! (although it's not clear why you want to weird)
• booleans
  • comparisons (e.g., 1 == 1 or 1 == 0)
    • you can compare strings (case sensative!)
    • also >, <, and !=
  • type() shows that the output of True or False is bool
  • e.g., "i" in "team"
  • e.g., "i" not in "team"
• if/elif/else
  • if, something that evaluates to a boolean, and then colon
  • e.g., if "mako" in "makoshark"
• functions
  • has a parentheses
  • we've already learnd examples of this: exit(), help(), type()

Lists

1. lists
   • purpose
   • initialization
   • len() review
   • accessing elements
   • adding elements
   • changing elements
   • slicing lists
   • strings are like lists
     • len()
       • len("") length of the empty string
2. loops and more flow control
   • for loops
   • if statements inside for loops
   • nested for loops
   • range()
   • while loops
   • infinite loops
   • if statements inside while loops
   • break
   • raw_input()
3. dictionaries
   • purpose
   • initialization
   • accessing elements
   • adding elements
   • changing elements
   • keys() and values()
4. modules
   • purpose
   • builtins
   • imports
   • import random
   • random.randint
   • random.choice
   • walk through state_capitals.py

Where state_capitals.py from http://mako.cc/teaching/2014/cdsw/state_capitals.py is the grand finale and synthesis of lecture material.