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()
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.
来源：https://stackoverflow.com/questions/18670795/r-boxplot-tilted-labels-x-axis