ggplot2r
I have a horizontal line in a ggplot and I would like to label it's value (7.1) on the y axis.
library(ggplot2)
df <- data.frame(y=c(1:10),x=c(1:10))
h <- 7.1
plot1 <- ggplot(df, aes(x=x,y=y)) + geom_point()
plot2 <- plot1+ geom_hline(aes(yintercept=h))
Thank you for your help.
Change the last line to
q + theme(axis.text.x = element_text(angle = 90, vjust = 0.5, hjust=1))
By default, the axes are aligned at the center of the text, even when rotated. When you rotate +/- 90 degrees, you usually want it to be aligned at the edge instead:
The image above is from this blog post.
As of ggplot2 0.9.2, this has become much easier to do using "themes." You can now assign themes separately to panel.grid.major.x and panel.grid.major.y, as demonstrated below.
# simulate data for the bar graph
data <- data.frame( X = c("A","B","C"), Y = c(1:3) )
# make the bar graph
ggplot( data ) +
geom_bar( aes( X, Y ) ) +
theme( # remove the vertical grid lines
panel.grid.major.x = element_blank() ,
# explicitly set the horizontal lines (or they will disappear too)
panel.grid.major.y = element_line( size=.1, color="black" )
)
The result of this example is quite ugly looking, but it demonstrates how to remove the vertical lines while preserving the horizontal lines and x-axis tick-marks.
Best Answer
It's not clear if you want 7.1 to be part of the y-axis, or if you just want a way to label the line. Assuming the former, you can use
scale_y_continuous()to define your own breaks. Something like this may do what you want (will need some fiddling most likely):Assuming the latter, this is probably more what you want: