EGR 103/Concept List

This page will be used to keep track of the commands and major concepts for each lecture in EGR 103.

Lecture 1 - Introduction

• Class web page: EGR 103L; assignments, contact info, readings, etc - see slides on Errata/Notes page
• Sakai page: Sakai 103L page; grades, surveys and tests, some assignment submissions
• CampusWire page: CampusWire 103L page; message board for questions - you need to be in the class and have the access code 6393 to subscribe.

Lecture 2 - Programs and Programming

• Seven steps of programming -
• Watch video on Developing an Algorithm
• Watch video on A Seven Step Approach to Solving Programming Problems
• To play with Python:
  • Install it on your machine or a public machine: Download
• Quick tour of Python
  • Editing window, variable explorer, and console
• You are not expected to remember any of the specifics about how Python stores things or works with them yet!

Lecture 3 - "Number" Types

• Python is a "typed" language - variables have types
• We will use eight types:
  • Focus of the day: int, float, and array
  • Focus a little later: string, list, tuple
  • Focus later: dictionary, set
• int: integers; Python can store these perfectly
• float: floating point numbers - "numbers with decimal points" - Python sometimes has problems
• array
  • Requires numpy, usually with import numpy as np
  • Organizational unit for storing rectangular arrays of numbers
• Math with "Number" types works the way you expect
  • ** * / // % + -
• Relational operators can compare "Number" Types and work the way you expect with True or False as an answer
  • < <= == >= > !=
  • With arrays, either same size or one is a single value; result will be an array of True and False the same size as the array
• Slices allow us to extract information from an array or put information into an array
• a[0] is the element in a at the start
• a[3] is the element in a three away from the start
• a[:] is all the elements in a because what is really happening is:
  • a[start:until] where start is the first index and until is just *past* the last index;
  • a[3:7] will return a[3] through a[6] in 4-element array
  • a[start:until:increment] will skip indices by increment instead of 1
  • To go backwards, a[start:until:-increment] will start at an index and then go backwards until getting at or just past until.
• For 2-D arrays, you can index items with either separate row and column indices or indices separated by commas:
  • a[2][3] is the same as a[2, 3]
  • Only works for arrays!

Lecture 4 - Other Types and Functions

• Lists are set off with [ ] and entries can be any valid type (including other lists!); entries can be of different types from other entries
• List items can be changed
• Tuples are indicated by commas without square brackets (and are usually shown with parentheses - which are required if trying to make a tuple an entry in a tuple or a list)
• Dictionaries are collections of key : value pairs set off with { }; keys can be any immutable type (int, float, string, tuple) and must be unique; values can be any type and do not need to be unique
• To read more:
  • Note! Many of the tutorials below use Python 2 so instead of print(thing) it shows print thing
  • Lists at tutorialspoint
  • Tuples at tutorialspoint
  • Dictionary at tutorialspoint
• Defined functions can be multiple lines of code and have multiple outputs.
  • Four different types of input parameters:
    • Required (listed first)
    • Named with defaults (second)
    • Additional positional arguments ("*args") (third)
      • Function will create a tuple containing these items in order
    • Additional keyword arguments ("**kwargs") (last)
      • Function will create a dictionary of keyword and value pairs
  • Function ends when indentation stops or when the function hits a return statement
  • Return returns single item as an item of that type; if there are multiple items returned, they are stored in a tuple
  • If there is a left side to the function call, it either needs to be a single variable name or a tuple with as many entries as the number of items returned

Lecture 5 - Format, Logic, Decisions, and Loops

• Creating formatted strings using {} and .format() (format strings, standard format specifiers) -- focus was on using e or f for type, minimumwidth.precision, and possibly a + in front to force printing + for positive numbers.
• Also - Format Specification Mini-Language
• Basics of decisions using if...elif...else
• Building a program to check for vowels, consonants, and y
• Bonus material:
  • Rhabarberbarbara - now with subtitles!
  • Rhabarberbarbara - live recording!
  • Lion-Eating Poet in the Stone Den - 施氏食獅史, or Shī Shì shí shī shǐ
  • Buffalo$$^8$$