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14 - Introduction to R

Slide Exercises

Plot kWh per square foot by year for the following University of Georgia data. Before starting, read the boxed insert in the book on smart editing.

year square feet kWh
2007 14,214,216 2,141,705
2008 14,359,041 2,108,088
2009 14,752,886 2,150,841
2010 15,341,886 2,211,414
2011 15,573,100 2,187,164
2012 15,740,742 2,057,364

year <-  c(2007, 2008, 2009, 2010, 2011, 2012)
sqfeet <-  c(14214216, 14359041, 14752886, 15341886, 15573100, 15740742)
kwh <-  c(2141705, 2108088, 2150841, 2211414, 2187164, 2057364)
kwhpersqft <-  kwh/sqfeet
plot(year,kwhpersqft)

Create a matrix with 6 rows and 3 columns containing the numbers 1 through 18.
m <-  matrix(1:18, nrow=6,ncol=3)

Install the measurement package and use one of its functions to do the following conversions:

library(measurement)
conv_unit(100,'F','C')
conv_unit(100,'m','ft')


Install the measurement package and run the preceding code.
# Create a new column with the temperature in Celsius
library(measurement)
url <- "http://people.terry.uga.edu/rwatson/data/centralparktemps.txt"
t <- read.table(url, header=T, sep=',')
# compute Celsius
t$Ctemp = round(conv_unit(t$temperature,'F','C'),1)

The saved file is available.


Using the Atlanta weather database and the lubridate package, compute the average temperature at 5 pm in August.
Determine the maximum temperature for each day in August across all years in the input file.
library(dplyr)
library(lubridate)
library(DBI)
conn <- dbConnect(RMySQL::MySQL(), "richardtwatson.com", dbname="Weather", user="db2", password="student")
# Query the database and create file t for use with R
t <- dbGetQuery(conn,"select * from record;")
t$year <- year(t$timestamp)
t$month <- month(t$timestamp)
t$hour <- hour(t$timestamp)
head(t) # Compute the average temperature at 5pm in August t %>% filter(hour==17 & month==8) %>% summarize(mean=mean(airTemp)) # Compute the maximum temperature for each day in August t$day <- day(t$timestamp)
t %>% filter(month==8) %>% group_by(day) %>% summarize(max=max(airTemp))

This page is part of the promotional and support material for Data Management (sixth edition) by Richard T. Watson
For questions and comments please contact the author

Date revised: 03-Apr-2017