I am trying to make a forest plot in R, displaying results from a meta-analysis. However, I run into problems using ggplot2. I have not found similar questions on stackoverflow so far and would really appreciate some help.
The code I am using now looks like this (I changed it a bit to make it self-containing):
cohort <- letters[1:15]
population <- c( runif(15, min=2000, max=50000)) #hit1$N
beta <- c( runif(15, min=-1, max=2))
lower95 <- c(runif(15, min=-1.5, max=0.5))
upper95 <- c(runif(15, min=1.5, max=2.5))
type <- c("CBCL","SDQ","CBCL","SDQ","CBCL","SDQ","CBCL")
data <- as.data.frame(cbind(cohort, population, beta ,lower95,upper95,type))
ggplot(data=data, aes(x=cohort, y=beta))+
geom_errorbar(aes(ymin=lower95, ymax=upper95), width=.667) +
geom_point(aes(size=population, fill=type), colour="black",shape=21)+
geom_hline(yintercept=0, linetype="dashed")+
scale_x_discrete(name="Cohort")+
coord_flip()+
scale_shape(solid=FALSE)+
scale_fill_manual(values=c( "CBCL"="white", "SDQ"="black"))+
labs(title="Forest Plot") +
theme_bw()
Now, I have the following issues:
- The x-axis is unreadable because all the values are overlapping.
- The legend to the right ('population') displays all the values, but I want it solely to display some arbitrary values, like 5000, 10000 and 15000.
- The plot should have a dashed line at y=0, but this line is displayed to the far right of the plot, which can't be right.
- I would like to add additional text columns to the right of each bar (to display additional info for each specific cohort).
- Any modifications to make the plot 'prettier' is always welcome.
Thanks in advance!