RinAction - R Data Manipulation - Creating New Variables

gistfile1.r

#-----------------------------------------------------------------------------#
#-----------------------------------------------------------------------------#
#                 R in Action - Data Management                               # 
#-----------------------------------------------------------------------------#
#-----------------------------------------------------------------------------#


install.packages(c('reshape', 'sqldf'))


# Create the data frame

manager <- c(1, 2, 3, 4, 5)
date <- c("10/24/08", "10/28/08", "10/1/08", "10/12/08", "5/1/09")
gender <- c("M", "F", "F", "M", "F")
age <- c(32, 45, 25, 39, 99)
q1 <- c(5, 3, 3, 3, 2)
q2 <- c(4, 5, 5, 3, 2)
q3 <- c(5, 2, 5, 4, 1)
q4 <- c(5, 5, 5, NA, 2)
q5 <- c(5, 5, 2, NA, 1)
leadership <- data.frame(manager, date, gender, age, q1, q2, q3, q4, q5, stringsAsFactors = FALSE)

# the individual vectors are no longer needed
rm(manager, date, gender, age, q1, q2, q3, q4, q5)

#################################################
##           Creating new variables            ##
##           - in the same data frame          ##
#################################################

# Method 1 --> create new vectors
mydata <- data.frame(x1 = c(2, 2, 6, 4), x2 = c(3,4, 2, 8))
mydata$sumx <- mydata$x1 + mydata$x2
mydata$meanx <- (mydata$x1 + mydata$x2)/2

# method 2 --> Using Attach/Detach
attach(mydata)
mydata$sumx <- x1 + x2
mydata$meanx <- (x1 + x2)/2
detach(mydata)

# Method 3 --> Using Transform() function
mydata <- transform(mydata, sumx = x1 + x2, meanx = (x1 + x2)/2)