So I understand how the apply function should be used but I am not sure how to integrate with an IF statement. Here is my attempt and can someone please push me in the right direction:
data <- mtcars
apply(data, 1, function(x) {
if (data$mpg < 20) {
data$colour <- "blue"
} else {
data$colour <- "red"
}
})
I just want to add a column to data for each row of the data frame for values in data$mpg between certain ranges.
You can do this using vectorization, which is preferred in R due to its speed:
data <- mtcars
data$colour <- ifelse(data$mpg < 20, data$colour <- "blue", data$colour <- "red")
This yields the following data.frame:
mpg cyl disp hp drat wt qsec vs am gear carb colour
Mazda RX4 21.0 6 160.0 110 3.90 2.620 16.46 0 1 4 4 red
Mazda RX4 Wag 21.0 6 160.0 110 3.90 2.875 17.02 0 1 4 4 red
Datsun 710 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1 red
Hornet 4 Drive 21.4 6 258.0 110 3.08 3.215 19.44 1 0 3 1 red
Hornet Sportabout 18.7 8 360.0 175 3.15 3.440 17.02 0 0 3 2 blue
Valiant 18.1 6 225.0 105 2.76 3.460 20.22 1 0 3 1 blue
Duster 360 14.3 8 360.0 245 3.21 3.570 15.84 0 0 3 4 blue
Merc 240D 24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2 red
Merc 230 22.8 4 140.8 95 3.92 3.150 22.90 1 0 4 2 red
Merc 280 19.2 6 167.6 123 3.92 3.440 18.30 1 0 4 4 blue
Merc 280C 17.8 6 167.6 123 3.92 3.440 18.90 1 0 4 4 blue
Merc 450SE 16.4 8 275.8 180 3.07 4.070 17.40 0 0 3 3 blue
Merc 450SL 17.3 8 275.8 180 3.07 3.730 17.60 0 0 3 3 blue
Merc 450SLC 15.2 8 275.8 180 3.07 3.780 18.00 0 0 3 3 blue
Cadillac Fleetwood 10.4 8 472.0 205 2.93 5.250 17.98 0 0 3 4 blue
Lincoln Continental 10.4 8 460.0 215 3.00 5.424 17.82 0 0 3 4 blue
Chrysler Imperial 14.7 8 440.0 230 3.23 5.345 17.42 0 0 3 4 blue
Fiat 128 32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1 red
Honda Civic 30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2 red
Toyota Corolla 33.9 4 71.1 65 4.22 1.835 19.90 1 1 4 1 red
Toyota Corona 21.5 4 120.1 97 3.70 2.465 20.01 1 0 3 1 red
Dodge Challenger 15.5 8 318.0 150 2.76 3.520 16.87 0 0 3 2 blue
AMC Javelin 15.2 8 304.0 150 3.15 3.435 17.30 0 0 3 2 blue
Camaro Z28 13.3 8 350.0 245 3.73 3.840 15.41 0 0 3 4 blue
Pontiac Firebird 19.2 8 400.0 175 3.08 3.845 17.05 0 0 3 2 blue
Fiat X1-9 27.3 4 79.0 66 4.08 1.935 18.90 1 1 4 1 red
Porsche 914-2 26.0 4 120.3 91 4.43 2.140 16.70 0 1 5 2 red
Lotus Europa 30.4 4 95.1 113 3.77 1.513 16.90 1 1 5 2 red
Ford Pantera L 15.8 8 351.0 264 4.22 3.170 14.50 0 1 5 4 blue
Ferrari Dino 19.7 6 145.0 175 3.62 2.770 15.50 0 1 5 6 blue
Maserati Bora 15.0 8 301.0 335 3.54 3.570 14.60 0 1 5 8 blue
Volvo 142E 21.4 4 121.0 109 4.11 2.780 18.60 1 1 4 2 red
A base based option using within:
head(within(mtcars,{
my_col <-ifelse(mpg < 20, "blue", "red")
}),3)
mpg cyl disp hp drat wt qsec vs am gear carb
Mazda RX4 21.0 6 160 110 3.90 2.620 16.46 0 1 4 4
Mazda RX4 Wag 21.0 6 160 110 3.90 2.875 17.02 0 1 4 4
Datsun 710 22.8 4 108 93 3.85 2.320 18.61 1 1 4 1
my_col
Mazda RX4 red
Mazda RX4 Wag red
Datsun 710 red
Or with sapply which in my experience is a bit faster than applying at a margin of 2:
mtcars$colour<-sapply(mtcars[,"mpg"], function(x) ifelse(x<20,"blue","red"))
#rm(mtcars)
#data(mtcars)
#restores mtcars^^
sapplynotapplyorapplywithin a margin of 2, applying onmpg.