Community Data Science Workshops (Fall 2014)/Day 1 lecture: Difference between revisions
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* purpose
** Stores things ''in order''
* initialization
** making a list called my list: <code>my_list = ["a", "b", "c"]</code>
** comma separated elements. in python they can be a mix of any kind of types
** <code>type(my_list)</code>
* <tt>len()</tt> review
* accessing elements
** indexing from 0 (now you understand all the zeros we've been using
* adding elements
* changing elements
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Revision as of 16:52, 8 November 2014
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
or1 == 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"
- comparisons (e.g.,
- if/elif/else (move to external file)
- if, something that evaluates to a boolean, and then colon
- e.g.,
if "mako" in "makoshark"
- e.g., adding else example:
if brother_age > sister_age
- e.g., tempreature 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!)
- functions
- has a parentheses
- we've already learnd examples of this: exit(), help(), type()
Lists
- purpose
- Stores things in order
- initialization
- making a list called my list:
my_list = ["a", "b", "c"]
- comma separated elements. in python they can be a mix of any kind of types
type(my_list)
- making a list called my list:
- len() review
- accessing elements
- indexing from 0 (now you understand all the zeros we've been using
- adding elements
- changing elements
- slicing lists
- strings are like lists
- len()
len("")
length of the empty string
- len()
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()
dictionaries
- purpose
- initialization
- accessing elements
- adding elements
- changing elements
- keys() and values()
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.