Hello,
In the following code, the fixed parts of the plot are drawn first,
assigning the plot to p. Then geom_hline is conditionally added to p and
the result returned to caller.
This may be a problem if the conditional geom needs to be in a specified
order in the plot. Function plotLineFunc2 adds everything in the order
of the question and is probably a better way of solving the problem.
I have also rewritten posNeg() without ifelse.
posNeg <- function(x) sum(x>0)>0 & sum(x>0)<length(x)
plotLineFunc <- function(MYdf,MYx,MYy) {
p <- ggplot(MYdf,aes(x={{MYx}},y={{MYy}}))+
geom_line(colour="black",size=0.5)
if(posNeg({{MYy}}))
p + geom_hline(yintercept=0,size=0.2)
else p
}
plotLineFunc2 <- function(MYdf,MYx,MYy) {
p <- ggplot(MYdf,aes(x={{MYx}},y={{MYy}}))
p <- if(posNeg({{MYy}}))
p + geom_hline(yintercept=0,size=0.2)
else p
p + geom_line(colour="black",size=0.5)
}
(plot1 <- plotLineFunc(df,a,b))
(plot2 <- plotLineFunc(df,a,c))
Hope this helps,
Rui Barradas
Às 02:24 de 25/03/21, p...@philipsmith.ca escreveu:
How can I write an R function that contains a call to ggplot within it,
with one of the ggplot geom statements being conditional? In my reprex,
I want the plot to contain a horizontal zero line if the y values are
both positive and negative, and to exclude the horizontal line if all of
the y values are of the same sign. I tried a simple if statement, but it
does not work. Suggestions appreciated. Philip
library(rlang)
library(tidyverse)
a <- c(1:8)
b <- c(23,34,45,43,32,45,68,78)
c <- c(0.34,0.56,0.97,0.33,-0.23,-0.36,-0.11,0.17)
df <- data.frame(a,b,c)
posNeg <- function(x) {
ifelse(sum(x>0)>0 & sum(x>0)<length(x), y <- TRUE,y <- FALSE)
}
plotLineFunc <- function(MYdf,MYx,MYy) {
ggplot(MYdf,aes(x={{MYx}},y={{MYy}}))+
#if(posNeg({{MYy}})) geom_hline(yintercept=0,size=0.2)+ # This
does not work
geom_line(colour="black",size=0.5)
}
(plot1 <- plotLineFunc(df,a,b))
(plot2 <- plotLineFunc(df,a,c))
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
