EGR 103/Concept List/F21
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Contents
Lecture 1
- Main class page: EGR 103L.
- See information on PDF of slide show on Errata / Notes page.
- Sakai page: Sakai 103L page; grades, surveys and tests, some assignment submissions
- Pundit page: EGR 103; reference lists
- CampusWire page: CampusWire 103L page; message board for questions - you need to be in the class and have the access code 8018 to subscribe.
Lecture 2 - Programs and Programming
- Almost all languages have input, output, math, conditional execution (decisions), and repetition (loops)
- Seven steps of programming The Seven Steps Poster
- Watch video on Developing an Algorithm
- Watch video on A Seven Step Approach to Solving Programming Problems
- Consider how to decide if a number is a prime number
- To play with Python:
- Install it on your machine or a public machine: Download
- Quick tour of Python
- Editing window, variable explorer, and console
- Main numerical types: whole numbers (int) and numbers with decimals (float)
- + - * // (rounded division) and % (remainder / modula) produce in if both sides are an int, float if either or both are floats
- / (regular division) and // (rounded division) produces float with ints or floats
- ** to do powers
- Python doesn't know everything to start with; may need to import things
import MODULE
means usingMODULE.function()
to runimport MODULE as NAME
means usingNAME.function()
to run
VAR = input("prompt: ")
will ask the user for a value and stores whatever they type as a stringNUM = int(VAR)
will convert the item in VAR to an integer if it looks like an integer; error otherwise
check back soon for an accurate page!
Lecture 1 - Course 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
- Pundit page: EGR 103; reference lists
- CampusWire page: CampusWire 103L page; message board for questions - you need to be in the class and have the access code 0878 to subscribe.
Lecture 2 - Programs and Programming
- Almost all languages have input, output, math, conditional execution, and repetition
- Seven steps of programming
- Watch video on Developing an Algorithm
- Watch video on A Seven Step Approach to Solving Programming Problems
- Consider how to decide if a number is a prime number
- 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
- Finished prime number checker - code is available in the Box drive for the class under Lectures / Lec03
- Looked at for loops for running code multiple times
- Looked at if...else trees for making decisions
- Created a variable to track whether we thought the number was prime
- Python is a "typed" language - variables have types. We will use several types:
- Focus of the day: int, float, and array
- Focus a little later: string, list, tuple
- Focus later: dictionary, set
- Focus way later: map, filter, zip
- int: integers; Python 3 can store these perfectly
- float: floating point numbers - "numbers with decimal points" - Python sometimes has problems storing floating point items exactly
- array
- Requires numpy, usually with
import numpy as np
- Organizational unit for storing rectangular arrays of numbers
- Generally create with np.array(LIST) where depth of nested LIST is dimensionality of array
- np.array([1, 2, 3]) is a 1-dimensional array with 3 elements
- np.array([[1, 2, 3], [4, 5, 6]]) is a 2-dimension array with 2 rows and 3 columns
- Requires numpy, usually with
- Math with "Number" types works the way you expect
- ** * / // % + -
- With arrays, * and / work element by element; *matrix* multiplication is a different character (specifically, @)
- 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 a collection or change information in mutable collections
- a[0] is the element in a at the start
- a[3] is the element in a three away from the start
- a[-1] is the last element of a
- a[-2] is the second-to-last element of a
- 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 a 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!