How to change the color of axes values in chart_Series()?

Question

I want to change the color of the vertical axes values like in this chart col.axis=4

par(bg = 1, fg = 2, col.axis=4)
plot(rnorm(10),t="b", col=8)

But I can't do the same with the chart_Series() function from quantmod package. As can be seen from the figure, only the horizontal axis changed color, but not the vertical axis.

library(quantmod)
p1 <- rnorm(8000) |> cumsum() |> xts(Sys.time()+1:8000) |> to.minutes(name = NULL) |> round(0)+100

par(bg = 1, fg = 2, col.axis=4)
th <- chart_theme()
th$col$dn.col <- "darkred"
th$col$up.col <- "darkgreen"
th$col$grid=NA
th$col$grid2=8
th$col$dn.border="#454545"
th$col$up.border="#454545"

chart_Series(p1, theme = th)

Answer 1

The parameter th$col$labels should do this, but the color is too hard-coded inside quantmod::chart_Series, so you have to alter the function. Use

my_chart_Series <- fix("chart_Series")

This opens an editor in which you can alter the line (around line 83)

cs$Env$theme$labels <- "#333333"

to the following one:

cs$Env$theme$labels <- theme$col$labels

After doing this, set the function into the correct namespace:

environment(my_chart_Series) <- asNamespace("quantmod")

Finally, convert your desired col.axis = 4 into HEX:

rgb2hex <- function(x) rgb(x[1], x[2], x[3], maxColorValue = 255)

> rgb2hex(col2rgb(4))
[1] "#2297E6"

and define

th$col$labels <- "#2297E6"

Your new function will then yield the desired output:

my_chart_Series(p1, theme = th)