33 arrange
Written by Isaac Ehrlich and last updated on 7 October 2021.
33.1 Introduction
Sometimes, you may want to view a dataset in a specific order. Data sets will often be displayed in the order the data were input, but you may want to view it sorted by a different variable. You can use the tidyverse arrange() function, to order a data set by a specific column.
33.2 arrange()
The arrange() function takes in a data frame and columns to sort by as its input, and will output the re-ordered data frame. arrange() does not modify any values in your data, it only changes the presentation.
Let’s take a look at a simple example using R’s mtcars data set:
head(mtcars)
#> mpg cyl disp hp drat wt qsec vs am
#> Mazda RX4 21.0 6 160 110 3.90 2.620 16.46 0 1
#> Mazda RX4 Wag 21.0 6 160 110 3.90 2.875 17.02 0 1
#> Datsun 710 22.8 4 108 93 3.85 2.320 18.61 1 1
#> Hornet 4 Drive 21.4 6 258 110 3.08 3.215 19.44 1 0
#> Hornet Sportabout 18.7 8 360 175 3.15 3.440 17.02 0 0
#> Valiant 18.1 6 225 105 2.76 3.460 20.22 1 0
#> gear carb
#> Mazda RX4 4 4
#> Mazda RX4 Wag 4 4
#> Datsun 710 4 1
#> Hornet 4 Drive 3 1
#> Hornet Sportabout 3 2
#> Valiant 3 1There’s a lot of information in this data, like miles per gallon, number of cylinders, and displacement, but it doesn’t seem to be ordered in any way.
Supposing we want to order the data frame by miles per gallon (i.e. see cars with lowest mpg at the top and highest mpg at the bottom), we can pass the following function:
head(arrange(mtcars, mtcars$mpg))
#> mpg cyl disp hp drat wt qsec vs
#> Cadillac Fleetwood 10.4 8 472 205 2.93 5.250 17.98 0
#> Lincoln Continental 10.4 8 460 215 3.00 5.424 17.82 0
#> Camaro Z28 13.3 8 350 245 3.73 3.840 15.41 0
#> Duster 360 14.3 8 360 245 3.21 3.570 15.84 0
#> Chrysler Imperial 14.7 8 440 230 3.23 5.345 17.42 0
#> Maserati Bora 15.0 8 301 335 3.54 3.570 14.60 0
#> am gear carb
#> Cadillac Fleetwood 0 3 4
#> Lincoln Continental 0 3 4
#> Camaro Z28 0 3 4
#> Duster 360 0 3 4
#> Chrysler Imperial 0 3 4
#> Maserati Bora 1 5 8Note, arrange() by default sorts in ascending order. If we want to sort in descending order, we can pass desc() to the column names:
head(arrange(mtcars, desc(mtcars$mpg)))
#> mpg cyl disp hp drat wt qsec vs am
#> Toyota Corolla 33.9 4 71.1 65 4.22 1.835 19.90 1 1
#> Fiat 128 32.4 4 78.7 66 4.08 2.200 19.47 1 1
#> Honda Civic 30.4 4 75.7 52 4.93 1.615 18.52 1 1
#> Lotus Europa 30.4 4 95.1 113 3.77 1.513 16.90 1 1
#> Fiat X1-9 27.3 4 79.0 66 4.08 1.935 18.90 1 1
#> Porsche 914-2 26.0 4 120.3 91 4.43 2.140 16.70 0 1
#> gear carb
#> Toyota Corolla 4 1
#> Fiat 128 4 1
#> Honda Civic 4 2
#> Lotus Europa 5 2
#> Fiat X1-9 4 1
#> Porsche 914-2 5 233.3 Additional Examples
33.3.1 Characters
arrange() can also sort by character vectors. In this case, arrange() by default will sort alphabetically. Let’s take a look at R’s HairEyeColor data set ordered by hair color:
HairEyeColor <- data.frame(HairEyeColor)
head(arrange(HairEyeColor, HairEyeColor$Hair))
#> Hair Eye Sex Freq
#> 1 Black Brown Male 32
#> 2 Black Blue Male 11
#> 3 Black Hazel Male 10
#> 4 Black Green Male 3
#> 5 Black Brown Female 36
#> 6 Black Blue Female 933.3.2 Multiple Arguments
If you pass multiple columns into arrange, it will order by columns in the order they are passed. For example, in the code below, we order the HairEyeColor first by hair color and then by frequency.
head(arrange(HairEyeColor, HairEyeColor$Hair, HairEyeColor$Freq))
#> Hair Eye Sex Freq
#> 1 Black Green Female 2
#> 2 Black Green Male 3
#> 3 Black Hazel Female 5
#> 4 Black Blue Female 9
#> 5 Black Hazel Male 10
#> 6 Black Blue Male 11We can see that the data was first ordered alphabetically by hair color, followed by frequency.
33.4 Practice Questions
For the following questions, please refer to R’s quakes data set:
head(quakes)
#> lat long depth mag stations
#> 1 -20.42 181.62 562 4.8 41
#> 2 -20.62 181.03 650 4.2 15
#> 3 -26.00 184.10 42 5.4 43
#> 4 -17.97 181.66 626 4.1 19
#> 5 -20.42 181.96 649 4.0 11
#> 6 -19.68 184.31 195 4.0 1233.5 Practice Coding
The following questions will ask you to use the arrange function on your own.
For these questions, please refer to R’s quakes data set:
head(quakes)
#> lat long depth mag stations
#> 1 -20.42 181.62 562 4.8 41
#> 2 -20.62 181.03 650 4.2 15
#> 3 -26.00 184.10 42 5.4 43
#> 4 -17.97 181.66 626 4.1 19
#> 5 -20.42 181.96 649 4.0 11
#> 6 -19.68 184.31 195 4.0 12- Arrange the data in quakes so that it is ordered by magnitude and then by stations, both in descending order
33.6 Special Cases and Common Errors
33.6.1 NA Values
Regardless of if you are sorting in ascending or descending order, NA values will be sent to the bottom of your reordered data frame.
33.6.2 Common Errors
The first input to arrange must be of type “data.frame,” it cannot be applied to objects that are tables or matrices. Make sure to convert to a data frame using
as.data.frame()if needed.Make sure you are properly calling your column names to order by. There are several ways to do this - the expressions below all output the same result.
arrange(quakes, quakes$mag)arrange(quakes, col = mag)quakes %>% arrange(mag)
Other errors are bound to pop up. Remember that Stack Overflow is your best friend!
33.7 Overview
arrange() is a useful function for reorganizing the structure of your data set. While it does not change any values, it may be useful if you need to order you data by a certain variable, or even just for easier viewing.