R: How To Draw Circles In Plots (With Examples) - - Statology

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You can use the following methods to draw a circle in a plot in R:

Method 1: Draw Circle Using Base R

library(plotrix) #create scatter plot plot(x, y) #add circle at specific (x, y) coordinates with specific radius draw.circle(x=3, y=8, radius=.5)

Method 2: Draw Circle Using ggplot2

library(ggplot2) library(ggforce) #create scatter plot with circle at specific location with specific radius ggplot(data = df, aes(x, y)) + geom_point() + geom_circle(aes(x0=3, y0=8, r=1), inherit.aes=FALSE) + coord_fixed()

The following examples shows how to use each method in practice.

Example 1: Draw Circle Using Base R

To draw a circle on a plot in base R, you need to first install and load the plotrix package:

install.packages('plotrix') library(plotrix)

Next, we can use the draw.circle() function from the plotrix package to add a circle to a scatter plot in base R:

#create data frame df <- data.frame(x=c(1, 2, 2, 3, 3, 4, 8), y=c(2, 4, 5, 4, 7, 9, 10)) #create scatter plot plot(df$x, df$y) #add circle draw.circle(x=3, y=8, radius=.5)

You can also use the draw.circle() function multiple times to plot multiple circles on the same plot:

#create data frame df <- data.frame(x=c(1, 2, 2, 3, 3, 4, 8), y=c(2, 4, 5, 4, 7, 9, 10)) #create scatter plot plot(df$x, df$y) #add multiple circles to plot draw.circle(x=3, y=8, radius=.5) draw.circle(x=4, y=5, radius=.5, border='red', col='lightblue', lwd=5, lty='dashed')

draw circle in plot in R

Notice that multiple circles have been added to the plot at the (x, y) coordinates that we specified.

Example 2: Draw Circle Using ggplot2

To draw a circle on a plot in ggplot2, you need to first install and load the ggplot2 and ggforce packages:

install.packages('ggplot2') install.packages('ggforce') library(ggplot2) library(ggforce)

Next, we can use the geom_circle() function from the ggforce package to add a circle to a scatter plot in ggplot2:

#create data frame df <- data.frame(x=c(1, 2, 2, 3, 3, 4, 8), y=c(2, 4, 5, 4, 7, 9, 10)) #create scatter plot with circle ggplot(data = df, aes(x, y)) + geom_point() + geom_circle(aes(x0=3, y0=8, r=1), linetype='dashed', color='red', fill='lightblue', lwd=1.5, inherit.aes=FALSE) + coord_fixed()

draw circle in ggplot2

The circle is placed in the exact (x, y) coordinates that we specified.

Note: If you don’t use the coord_fixed() argument, the circle may appear as an ellipse instead.

Additional Resources

The following tutorials explain how to perform other common tasks in R:

How to Create a Scatterplot in R with Multiple Variables How to Label Points on a Scatterplot in R How to Add a Regression Equation to a Plot in R

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