在特定X轴上以R绘制平均值

Question

In R, is there a way to add means to a plot at specific x-axis. For example, I want to do something like:

plot(1, 1, xlim = c(0, 6.5), ylim = c(0,300), type = 'n', xlab = '', ylab = '', xaxt = 'n') #xaxs="i",yaxs="i")
boxplot(dataset,at = 0.5, add = T, range = 6,yaxt = 'n')
points(mean(dataset), at = 0.5, add = T)

I get a message saying "at" and "add" are 'not a graphical parameter'. Is there a workaround?

So I am using RStudio. There are six different values (data_a, data_b, data_c, data_d, data_e, and data_f) each with 11 numbers. My current code looks like follows:

par(xpd = FALSE)
par(mar=c(8,4.5,2,1))
plot(1, 1, xlim = c(0, 6.5), ylim = c(0,300), type = 'n', xlab = '', ylab = '', xaxt = 'n') #xaxs="i",yaxs="i")
boxplot(data_a,at = 0.5, add = T, range = 6,yaxt = 'n')
boxplot(data_b,at = 1.5, add = T, range = 6,yaxt = 'n')
boxplot(data_c,at = 2.5, add = T, range = 6,yaxt = 'n')
boxplot(data_d,at = 4, add = T, range = 6,yaxt = 'n')
boxplot(data_e,at = 5, add = T, range = 6,yaxt = 'n')
boxplot(data_f,at = 6, add = T, range = 6,yaxt = 'n')
axis(2, at = 150, pos = -0.65, tck = 0, labels = 'X axis label',cex.axis=1.1)
axis(1, at = c(0.5,1.5,2.5,4,5,6),labels=c('','','','','',''))
axis(1, at = c(1.5,5),pos= -25,labels=c('label 1','labe 2'),tick=FALSE)
axis(1, at = c(3.25),labels=c(''),tck=-0.15)
axis(1, at = c(3.25),pos = -50,labels=c('Y axis label'),tick=FALSE)
abline(v=3.25)
par(xpd = NA)
text(0.5,-30, expression("a))
text(1.5,-30, expression("b"))
text(2.5,-30,"c")
text(4,-30, expression(d))
text(5,-30, expression("e"))
text(6,-30,"f")

Now I want to be able to add mean.

Answer 1

With boxplots, the location of the plots on the x axis are at the units (1, 2, 3, etc.). You can check this using the function locator() .

Here is an example to add means as a red circle to a boxplot using the iris dataset:

boxplot(Sepal.Length ~ Species,  data = iris)
points(seq_along(levels(iris$Species)), with(iris, tapply(Sepal.Length, Species, mean)), col = "red")

Answer 2

You can try this to get the desired plot (with randomly generated data_a, data_b etc.):

par(xpd = FALSE)
par(mar=c(8,4.5,2,1))
plot(1, 1, xlim = c(0, 6.5), ylim = c(0,300), type = 'n', xlab = '', ylab = '', xaxt = 'n') #xaxs="i",yaxs="i")
data_a <- runif(11, 0, 300)
data_b <- runif(11, 0, 300)
data_c <- runif(11, 0, 300)
data_d <- runif(11, 0, 300)
data_e <- runif(11, 0, 300)
data_f <- runif(11, 0, 300)
boxplot(data_a,at = 0.5, add = T, range = 6,yaxt = 'n')
boxplot(data_b,at = 1.5, add = T, range = 6,yaxt = 'n')
boxplot(data_c,at = 2.5, add = T, range = 6,yaxt = 'n')
boxplot(data_d,at = 4, add = T, range = 6,yaxt = 'n')
boxplot(data_e,at = 5, add = T, range = 6,yaxt = 'n')
boxplot(data_f,at = 6, add = T, range = 6,yaxt = 'n')
axis(2, at = 150, pos = -0.65, tck = 0, labels = 'X axis label',cex.axis=1.1)
axis(1, at = c(0.5,1.5,2.5,4,5,6),labels=c('','','','','',''))
axis(1, at = c(1.5,5),pos= -25,labels=c('label 1','label 2'),tick=FALSE)
axis(1, at = c(3.25),labels=c(''),tck=-0.15)
axis(1, at = c(3.25),pos = -50,labels=c('Y axis label'),tick=FALSE)
abline(v=3.25)
par(xpd = NA)
text(0.5,-30, expression("a"))
                         text(1.5,-30, expression("b"))
                         text(2.5,-30,"c")
                         text(4,-30, expression("d"))
                         text(5,-30, expression("e"))
                         text(6,-30,"f")
points(c(0.5,1.5,2.5,4,5,6), c(mean(data_a), mean(data_b), mean(data_c), mean(data_d), mean(data_e), mean(data_f)), pch = 22, col = "darkgrey", lwd = 7)