I am learning R and I follow the code in the book, Discovering Statistics Using R:
lecturerData<-read.delim("Lecturer Data.dat", header = TRUE); lecturerData
lecturerData$job<-factor(lecturerData$job, levels = c(1:2), labels = c("Lecturer", "Student")); lecturerData
lecturerOnly <- lecturerData[job=="Lecturer",]
lecturerOnly
However, the output is a bunch of "NA."
So I modify the code to the following:
lecturerData<-read.delim("Lecturer Data.dat", header = TRUE); lecturerData
lecturerData$job<-factor(lecturerData$job, levels = c(1:2), labels = c("Lecturer", "Student")); lecturerData
lecturerOnly <- lecturerData[**lecturerData$job**=="Lecturer",]
lecturerOnly
Then it works. (Show an output of rows with job = "Lecturer" only.)
I am wondering if it is supposed to be
lecturerOnly <- lecturerData[lecturerData$job=="Lecturer",]
instead of
lecturerOnly <- lecturerData[job=="Lecturer",]
Or did I do something wrong?
Thank you for your help.