how can you rotate the labels of the x axis for boxplot in r? I know which code to use but I can't apply it:
text(**????**, par("usr")[3] - 0.25, srt = 45, adj = 1, labels = labels, xpd = TRUE)
What variable goes where I have the question marks? I created this boxplot:
using this code:
soil=read.csv("soil_temp_boxplot.csv", header=TRUE, sep=";")
tiff("soil_boxplot.tiff")
par(mar=c(5.5,3.5,0.5,0.5))
labels<-paste(c("RB-GL830-[16]-10","RB-GL830-[16]-30", "SB-GL834-[11]-10","SB-GL834-[11]-30", "RB-GL843-[17]-10","RB-GL843-[17]-30","SB-GL864-[12]-10","SB-GL864-[12]-30","SB-GL989-[10]-30", "RB-F844-[18]-10", "RB-F844-[18]-30", "SBB-F-864-[14]-10","SB-F991-[13]-10", "SB-F991-[13]-30"))
boxplot(soil$rb.gl.10.830.16, soil$rb.gl.30.830.16, soil$sb.gl.10.834.11, soil$sb.gl.30.834.11, soil$rb.gl.10.843.17, soil$rb.gl.30.843.17, soil$sb.gl.10.864.12, soil$sb.gl.30.864.12, soil$sb.gl.30.989.10, soil$rb.f.10.844.18, soil$rb.f.30.844.18, soil$sbb.f.10.864.14, soil$sb.f.10.991.13, soil$sb.f.30.991.13, yaxt="n", col=c("darkolivegreen1","darkolivegreen4","darkolivegreen1","darkolivegreen4","darkolivegreen1","darkolivegreen4","darkolivegreen1","darkolivegreen4","darkolivegreen1","burlywood2","burlywood4","burlywood2","burlywood2", "burlywood4"))
axis(1, labels = TRUE)
axis(2, c(0, 8, c(1, 2, 3, 4, 5,6,7)), las=1)
text(labels, par("usr")[3] - 0.25, srt = 45, adj = 1, labels = labels, xpd = TRUE)
mtext(2, text="Soil Temperature [°C]", line=2.2)
mtext(1, text="Location", line=4.5)
dev.off()
To rotate x-axis text labels, we use “axis. text. x” as argument to theme() function. And we specify “element_text(angle = 90)” to rotate the x-axis text by an angle 90 degree.
To set labels for X and Y axes in R plot, call plot() function and along with the data to be plot, pass required string values for the X and Y axes labels to the “xlab” and “ylab” parameters respectively. By default X-axis label is set to “x”, and Y-axis label is set to “y”.
Label rotation For that we will use the srt argument to the text function. With srt , we can specify the text rotation in degrees, so srt = 35 would rotate the axis labels by 35 degrees.
To change the axis scales on a plot in base R, we can use the xlim() and ylim() functions.
An alternative following your original text
expression:
par(mar=c(6, 4.1, 4.1, 2.1))
labels <- paste(c("RB-GL830-[16]-10",
"RB-GL830-[16]-30",
"SB-GL834-[11]-10",
"SB-GL834-[11]-30",
"RB-GL843-[17]-10",
"RB-GL843-[17]-30"))
boxplot(count ~ spray, data = InsectSprays,
col = "lightgray", xaxt = "n", xlab = "")
# x axis with ticks but without labels
axis(1, labels = FALSE)
# Plot x labs at default x position
text(x = seq_along(labels), y = par("usr")[3] - 1, srt = 45, adj = 1,
labels = labels, xpd = TRUE)
Why use x = seq_along(labels)
for label positions? The x
in text
is a vector of coordinates where to put the labels. If you look at ?boxplot
, you find that the at
argument is a "numeric vector giving the locations where the boxplots should be drawn [...]; defaults to 1:n where n is the number of boxes." Because we haven't specified the at
argument in the boxplot
call, the default "1:n positions" will be used. The number of boxes is of course the number of levels of your explanatory variable, which @Josh O'Brien used in his answer. To show you an alternative, I used your customized label vector instead (which of course must have the same length as the number of factor levels). seq_along
generates a regular sequence from 1 to length
of the argument, which corresponds to the "defaults to 1:n" at
positions.
A side-note: your data seem to be in a 'wide' format. In many instances in R, it is more convenient to have the data in a 'long' format. In the plot
function, you then only need to specify your x variable (e.g. location) and y variable (e.g. soil temp), instead of specifying data for every single level of x.
Look at the staxlab
function in the plotrix package, it makes this (and an alternative) fairly straight forward.
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