[R] ggplot 3-color gradient scales

[April Ettington]

Thank you so much!


On Mon, Aug 24, 2020 at 5:33 PM Rui Barradas <ruipbarradas using sapo.pt> wrote:

> Hello,
>
> Note that the midpoint argument can make a big difference. In the code
> below try commenting out the line where the default is changed.
>
>
> f <- function(x){
>    (x - min(x))/(max(x) - min(x))
> }
>
> library(ggplot2)
>
> df1 <- iris[3:5]
> names(df1)[1:2] <- c("x", "y")
> df1$z <- ave(df1$y, df1$Species, FUN = f)
>
> ggplot(df1) +
>    geom_point( aes(x, y, color = z) ) +
>    scale_color_gradient2(low = "red",
>                          mid = "yellow",
>                          high = "blue",
>                          midpoint = 0.5
>                          )
>
> Hope this helps,
>
> Rui Barradas
>
>
> Às 04:43 de 24/08/20, Jeff Newmiller escreveu:
> > Check out scale_colour_gradient2()
> >
> > On August 23, 2020 8:12:06 PM PDT, April Ettington <
> aprilettington using gmail.com> wrote:
> >> Currently I am using these settings in ggplot to make a gradient from
> >> red
> >> to blue.
> >>
> >> geom_point( aes(x, y, color=z) ) +
> >> scale_colour_gradient(low = "red",high = "blue") +
> >>
> >> z is a ratio, and currently I am able to identify which have high and
> >> low
> >> values, but I'd really like to be able to distinguish which are >1, <1,
> >> or
> >> close to 1 by color.  It would be great if I could set a middle color
> >> in
> >> this gradient (eg. green) that is set the the value of 1, even if that
> >> is
> >> not the exact midpoint between my highest and lowest values.  Is there
> >> a
> >> way to do this in R?
> >>
> >> Thank you,
> >> April
> >>
> >>      [[alternative HTML version deleted]]
> >>
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> >
>

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