Cowplot

Ever wondered if you can put multiple plots in different alignment as plot-grids in R.

  • Cowplot is something which can do that for you.
  • Lets make some plots and see how we can arrange them using cow plot.
  • For plotting we are going to use inbuilt R dataset : mtcars
mtcars
##                      mpg cyl  disp  hp drat    wt  qsec vs am gear carb
## Mazda RX4           21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4
## Mazda RX4 Wag       21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4
## Datsun 710          22.8   4 108.0  93 3.85 2.320 18.61  1  1    4    1
## Hornet 4 Drive      21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1
## Hornet Sportabout   18.7   8 360.0 175 3.15 3.440 17.02  0  0    3    2
## Valiant             18.1   6 225.0 105 2.76 3.460 20.22  1  0    3    1
## Duster 360          14.3   8 360.0 245 3.21 3.570 15.84  0  0    3    4
## Merc 240D           24.4   4 146.7  62 3.69 3.190 20.00  1  0    4    2
## Merc 230            22.8   4 140.8  95 3.92 3.150 22.90  1  0    4    2
## Merc 280            19.2   6 167.6 123 3.92 3.440 18.30  1  0    4    4
## Merc 280C           17.8   6 167.6 123 3.92 3.440 18.90  1  0    4    4
## Merc 450SE          16.4   8 275.8 180 3.07 4.070 17.40  0  0    3    3
## Merc 450SL          17.3   8 275.8 180 3.07 3.730 17.60  0  0    3    3
## Merc 450SLC         15.2   8 275.8 180 3.07 3.780 18.00  0  0    3    3
## Cadillac Fleetwood  10.4   8 472.0 205 2.93 5.250 17.98  0  0    3    4
## Lincoln Continental 10.4   8 460.0 215 3.00 5.424 17.82  0  0    3    4
## Chrysler Imperial   14.7   8 440.0 230 3.23 5.345 17.42  0  0    3    4
## Fiat 128            32.4   4  78.7  66 4.08 2.200 19.47  1  1    4    1
## Honda Civic         30.4   4  75.7  52 4.93 1.615 18.52  1  1    4    2
## Toyota Corolla      33.9   4  71.1  65 4.22 1.835 19.90  1  1    4    1
## Toyota Corona       21.5   4 120.1  97 3.70 2.465 20.01  1  0    3    1
## Dodge Challenger    15.5   8 318.0 150 2.76 3.520 16.87  0  0    3    2
## AMC Javelin         15.2   8 304.0 150 3.15 3.435 17.30  0  0    3    2
## Camaro Z28          13.3   8 350.0 245 3.73 3.840 15.41  0  0    3    4
## Pontiac Firebird    19.2   8 400.0 175 3.08 3.845 17.05  0  0    3    2
## Fiat X1-9           27.3   4  79.0  66 4.08 1.935 18.90  1  1    4    1
## Porsche 914-2       26.0   4 120.3  91 4.43 2.140 16.70  0  1    5    2
## Lotus Europa        30.4   4  95.1 113 3.77 1.513 16.90  1  1    5    2
## Ford Pantera L      15.8   8 351.0 264 4.22 3.170 14.50  0  1    5    4
## Ferrari Dino        19.7   6 145.0 175 3.62 2.770 15.50  0  1    5    6
## Maserati Bora       15.0   8 301.0 335 3.54 3.570 14.60  0  1    5    8
## Volvo 142E          21.4   4 121.0 109 4.11 2.780 18.60  1  1    4    2

#For plotting we will use ggplot2 package (If you already have the package, you can simply load the package using library function, or else you have to install the package using “install.packages(“ggplot2”) function and then load the library)

library(ggplot2)

1st plot:mpg vs cyl

ggplot(mtcars, aes(cyl, mpg)) + geom_point()

2nd plot:

ggplot(mtcars, aes(hp, disp)) + geom_point()

3rd plot: hp vs cyl

ggplot(mtcars, aes(cyl, hp)) + geom_point()

Now lets say we want all the three graphs in one plot or in a grid. For that, before beginning, lets give unique name to each plots so that we can order/arrange them accordingly.

P <- ggplot(mtcars, aes(cyl, mpg)) + geom_point()
Q <- ggplot(mtcars, aes(hp, disp)) + geom_point()
R <- ggplot(mtcars, aes(cyl, hp)) + geom_point()

Now we have renamed all the three graphs, we can use cowplot package to arrange them. For that we need to load the library of cowplot if you had already installed the pacakge or if you don’t have then you have to install the package and then load the library.

library(cowplot)

Now we will use plot_grid function to arrange the graphs accordingly

1. Arranging the plot

plot_grid(P, Q, R, labels = "auto") #you can rename the labels accordingly or you can put auto argument which will name them automatically.

  1. Now lets say you don’t want auto labels, you want to name them specifically. So we will change the labels to P, Q and R to name them accordingly.
plot_grid(P, Q, R, labels = c("P", "Q", "R"))
  1. Now lets say you want all the three graphs in one single strips. so we will use ncol function to do that. we will make three columns to fit three graphs in one plate
plot_grid(P, Q, R, labels=c("P", "Q", "R"), ncol=3)
  1. Now lets say you want to change the labels size for all the graphs. For that you can use labels size function and accordingly modify the size.
plot_grid(P, Q, R, labels=c("P", "Q", "R"), ncol=3, label_size = 12)
  1. Now how about plotting all the three graphs in vertical direction rather than horizontal. For that we will use “nrow” function instead of ncol.
plot_grid(P, Q, R, labels=c("P", "Q", "R"), nrow=3)

Hope this will be helpful. If you have any more specific question you type in the comments.

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