## -----------------------------------------------------------------------------
d <- data.frame(id=1:10, 
        name=c('Bob', 'Bobby', '???', 'Bob', 'Bab', 'Jim', 'Jim', 'jim', '', 'Jim'), 
		score1=c(8, 10, 7, 9, 2, 5, 1, 6, 3, 4), 
		score2=c(3,4,5,-999,5,5,-999,2,3,4), stringsAsFactors=FALSE)
d


## -----------------------------------------------------------------------------
summary(d)


## -----------------------------------------------------------------------------
# which values in score2 are -999?
i <- d$score2 == -999
# set these to NA
d$score2[i] <- NA
summary(d)


## -----------------------------------------------------------------------------
unique(d$name)
table(d$name)


## -----------------------------------------------------------------------------
d$name[d$name %in% c("Bab", "Bobby")] <- "Bob"
table(d$name)


## -----------------------------------------------------------------------------
# get the first letters
first <- substr(d$name, 1, 1)
# get the remainder
remainder <- substr(d$name, 2, nchar(d$name))
# assure that the first letter is upper case
first <- toupper(first)
# combine
name <- paste0(first, remainder)
# assign back to the variable
d$name <- name
table(d$name)


## -----------------------------------------------------------------------------
d$name[d$name == "???"] <- NA
table(d$name)


## -----------------------------------------------------------------------------
table(d$name, useNA="ifany")


## -----------------------------------------------------------------------------
d$name[9]


## -----------------------------------------------------------------------------
d$name[d$name == ""] <- NA
table(d$name, useNA="ifany")


## -----------------------------------------------------------------------------
table(d[ c("name", "score2")])


## -----------------------------------------------------------------------------
quantile(d$score1)
range(d$score1)
mean(d$score1)


## -----------------------------------------------------------------------------
quantile(d$score2)
range(d$score2)
quantile(d$score2, na.rm=TRUE)
range(d$score2, na.rm=TRUE)


## ----plot1, fig.cap=""--------------------------------------------------------
par(mfrow=c(2,2))
plot(d$score1, d$score2)
boxplot(d[, c("score1", "score2")])
plot(sort(d$score1))
hist(d$score2)