Ji_Soo_Song_Lab_1.R

#LAb 1, Ji Soo Song

#Enable the dplyr package. 
library(dplyr)

#Define a vector with 10 authors' last names.
authorLastName<-c('Kim','Andrews','McDonald','Johnson','Bryant','Stein','Rodriguez','Li','Ali','Watson')
#Define a vector with one book written by each author.
title<-c('Lost Men','Of Cites and States','Gone','International Comparisons','Why?','Dunkirk','Soar','Wings of Liberty','Abacus','Lilac')
#Define a vector with the publication years of the above books.
pYear<-c(1954,1933,1957,2003,2011,2014,1954,1957,1966,1954)
#Define a vector with the number of each book in stock. 
nStock<-c(2,9,32,4,12,54,12,4,98,84)
#Define a vector with the price of each book.
dollarPrice<-c(11,12,23,8,22,7,21,14,18,12)

#Put together all defined vectors into a data frame. 
bookstore<-data.frame(authorLastName,title,pYear,nStock,dollarPrice)
#Display unsorted data frame.
View(bookstore)

#Sort the original data frame by descending year of publication.
#And within same year of publication, sort by ascending order of author last name.
sortedBookstore <- bookstore%>%arrange(-pYear,authorLastName)
#Display the sorted data frame. 
View(sortedBookstore)

#Mutate command used to add the sale price column.
#First check if a row has nStock above 10 and pYear below 1970. If true, apply a 50% discount.
#If false, check if a row has nStock less than 10 and pYear below 1970. If trre, apply a 25% discount. 
#If false, check if a row has nStock more than 10 and pYear above 1970. If true, apply a 40% discount.
#In all other cases, keep original price as the sale price. 
saleBookstore <- bookstore%>%mutate(saleDollarPrice=ifelse(nStock>10 & pYear<1970,dollarPrice*0.5,ifelse(nStock<10 & pYear<1970,dollarPrice*0.75,ifelse(pYear>1970 & nStock>10,dollarPrice*0.6,dollarPrice))))
#Display the data frame with the sale price column added. 
View(saleBookstore)

#Filter the rows where nStock is above 10 and pYear is below 1970 (i.e. the dicounted books).
subBookstore <- saleBookstore%>%filter(nStock>10 | pYear<1970)
#From these rows, select only the author last name, book title, and sale price columns.
subsubBookstore <- subBookstore%>%select(authorLastName,title,saleDollarPrice) 
#Display this filtered and selected data frame. 
View(subsubBookstore)