R: ggplot: two plots in one dataframe: color one plot only when it is less than the other plot-CodePudding

I have two geom_point plots from a single dataframe on a plot. What I want is to only color label when plot 2 is below plot 1 on the y axis. So if it is above, plot2 would be grey/black, when it is below, it will be labeled by a certain column in the dataframe

df <- setNames(data.frame(c("2022-07-29 00:00:00","2022-07-29 00:00:05",
                           "2022-07-29 00:05:00","2022-07-29 00:05:05",
                           "2022-07-29 00:10:00","2022-07-29 00:15:00",
                           "2022-07-29 00:20:00","2022-07-29 00:20:05"), 
                          c(1,2,3,4,5,6,7,8), 
                          c(0.8,2.1,2.5,4.1,5,6.1,6.9,8.1),
                          c("a","a","b","b","b","b","b","c")),
                          c("timeStamp", "value1", "value2", "text"))

So the closest graph I can come up with is

ggplot(df)  
geom_point(aes(timeStamp,value1)) 
geom_point(aes(timeStamp, value2, color=value2>value1))  
scale_color_manual(name="callout", values = setNames(c('green','red'), c(T,F)))

This plot is almost exactly what I need, but I want the red line that is below the first plot to use the text column to label. If i changed the setNames above to c('green', text), I thought it should work but doesn't and cant figure out the correct way forward. Thank you

CodePudding user response：

Here's my interpretation of what you want. The key line is

callout <- factor(ifelse(df$value2 > df$value1, NA, df$text))

which sets a colour to the text column if value2 is less than value1.

library(ggplot2)
df <-
    setNames(data.frame(
        as.POSIXct(
            c(
            "2022-07-29 00:00:00",
            "2022-07-29 00:00:05",
            "2022-07-29 00:05:00",
            "2022-07-29 00:05:05",
            "2022-07-29 00:10:00",
            "2022-07-29 00:15:00",
            "2022-07-29 00:20:00",
            "2022-07-29 00:20:05"
            )),
        c(1, 2, 3, 4, 5, 6, 7, 8),
        c(0.8, 2.1, 2.5, 4.1, 5, 6.1, 6.9, 8.1),
        c("a", "a", "b", "b", "b", "b", "b", "c")
    ),
    c("timeStamp", "value1", "value2", "text"))

# this works out the colours
callout <- factor(ifelse(df$value2 > df$value1, NA, df$text))

gg2 <- 
    ggplot(df)   
    geom_point(aes(timeStamp,value1), col='grey50', size=3)   
    geom_point(aes(timeStamp, value2, color = callout), size=3) 

gg2

I also added the as.POSIXct() call which makes the x axis neater.