Publications by Donny Lofland
DATA605 - Homework Assignment 2
Source files: [https://github.com/djlofland/DATA605_S2020/tree/master/] Problem Set 1 Show that \(A^{T}A \ne AA^{T}\) in general: \[\text{Given: }A = \left[\begin{array}\\ a & b\\ c & d\\\end{array}\right]\ \text{then}\ A^{T} = \left[\begin{array}\\ a & c\\ b & d\\\end{array}\right]\\ \text{show} \ A^{T}A \ne AA^{T}\\ \left[\begin{array}\\ a &...
2175 sym R (1969 sym/2 pcs)
Data 606 - Lab 6 Inference
In August of 2012, news outlets ranging from the Washington Post to the Huffington Post ran a story about the rise of atheism in America. The source for the story was a poll that asked people, “Irrespective of whether you attend a place of worship or not, would you say you are a religious person, not a religious person or a convinced atheist?�...
13062 sym R (5253 sym/40 pcs) 10 img
DATA607 - Week 12 (MongoDB)
Source files: https://github.com/djlofland/DATA607_F2019/tree/master/Week12 Assignment For this assignment, you should take information from a relational database and migrate it to a NoSQL database of your own choosing. For the relational database, you might use the flights database, the tb database, the “data skills” database your team crea...
837 sym R (1671 sym/5 pcs)
DATA607-FinalProject
Part 1 - Introduction One of the many wonderful aspects of the United States of America is its diversity of people and culture. Historically, outside of major port and immigration centers, cultures tend to be clustered geographically. This will manifest not only in genetic differences, but also in differences in diet and activity. A question can ...
19466 sym R (31515 sym/38 pcs) 25 img
DATA606 - Final Project
Source files: https://github.com/djlofland/DATA606_F2019/tree/master/FinalProject knitr::opts_chunk$set(echo = TRUE, collapse = TRUE, warning = FALSE) library(tidyverse) library(formattable) # Pretty print tables library(scales) library(caret) library(corrr) library(Hmisc) library(corrplot) library(glmnet) library(choroplethr) library(maps) libr...
17920 sym R (39788 sym/56 pcs) 38 img 7 tbl
DATA ^)^ Lab 9 - Multiple Linear Regression
Grading the professor Many college courses conclude by giving students the opportunity to evaluate the course and the instructor anonymously. However, the use of these student evaluations as an indicator of course quality and teaching effectiveness is often criticized because these measures may reflect the influence of non-teaching related charac...
13994 sym R (9440 sym/35 pcs) 21 img 1 tbl
DATA605 - Homework Assignment 1
Problem Set 1 You can think of vectors representing many dimensions of related information. For instance, Netflix might store all the ratings a user gives to movies in a vector. This is clearly a vector of very large dimensions (in the millions) and very sparse as the user might have rated only a few movies. Similarly, Amazon might store the item...
2442 sym R (1460 sym/18 pcs)
DATA605 - Discussion Problem 3 (EE C12 p 388)
EE C12 Find the characteristic polynomial of the matrix: \[A = \left[\begin{array}\\1 & 2 & 1 & 0\\ 1 & 0 & 1 & 0\\ 2 & 1 & 1 & 0\\ 3 & 1 & 0 & 1\\ \end{array}\right]\] Then the characteristic polynomial of \(A\) is the polynomial \(p_{A} (x)\) defined by: \[p_{A} (x) = det (A -xI{_n})\] Solve: \[\begin{align} p_{A} (x) &= det (A -xI{_n})\\ p_{A}...
1756 sym
DATA605 - Homework Assignment 3
Source files: [https://github.com/djlofland/DATA605_S2020/tree/master/] Problem Set 1 What is the rank of matrix \(A\)? \[A = \left[\begin{array}\\ 1 & 2 & 3 & 4\\ -1 & 0 & 1 & 3\\ 0 & 1 & -2 & 1\\ 5 & 4 & -2 & -3\\\end{array}\right]\] Rank: 4 since it is a square matrix and no rows are scalar equivalents or can be formed by combining other r...
4211 sym R (1108 sym/13 pcs)
DATA605 - Homework 6
knitr::opts_chunk$set(echo = TRUE) library(tinytex) library(pracma) Source files: [https://github.com/djlofland/DATA605_S2020/tree/master/] Problem Set 1 A box contains 54 red marbles, 9 white marbles, and 75 blue marbles. If a marble is randomly selected from the box, what is the probability that it is red or blue? Express your answer as a fra...
4398 sym R (5352 sym/37 pcs)