Select data with subset or with $

days <- c('Mon', 'Tue', 'Wed', 'Thur', 'Fri')
temp <- c(20, 30, 20, 24, 25)
rain <- c(T, F, F, F, T)
df <- data.frame(days, temp, rain)
print(df)

subset(df, subset = temp > 20)

# new.df <- df[df$temp > 20, ]
# print(new.df)


# Ex 10: What is the average mpg for cars that have more than 100 hp AND a wt value of more than 2.5.
# avg <- mean(mtcars$mpg[mtcars$hp > 100 & mtcars$wt > 2.5])
# avg <- mean(subset(mtcars, subset = hp > 100 & wt > 2.5)$mpg)