Hello,
If you want a predetermined number of colors, discretise the data and
use scale_color_manual. In the code below I first compute another vector
z, with a different range, 0 to 2. (In my first mail it was 0 to 1.)
g <- function(x, a = 0, b = 1){
(b - a)*(x - min(x))/(max(x) - min(x)) + a
}
library(ggplot2)
df1 <- iris[3:5]
names(df1)[1:2] <- c("x", "y")
df1$z <- ave(df1$y, df1$Species, FUN = function(x) g(x, a = 0, b = 2))
Now is the step that solves the problem, to bin the vector. Other
options could include findInterval. Then the two plot instructions are
equivalent.
df1$z <- cut(df1$z,
breaks = c(-Inf, 0.8, 1.2, Inf),
labels = c("Small", "Medium", "Large"))
ggplot(df1) +
geom_point( aes(x, y, color = z) ) +
scale_color_manual(values = c("red", "green", "blue"))
ggplot(df1) +
geom_point( aes(x, y, color = z) ) +
scale_color_manual(breaks = c("Small", "Medium", "Large"),
values = c("Small" = "red", "Medium" = "green",
"Large" = "blue"))
Hope this helps,
Rui Barradas
Às 10:38 de 25/08/20, April Ettington escreveu:
Is there a way to set it to 3 color categories instead of a gradient?
Like if the color is based on the numbers in a dataframe column, can I
make it so anything >1.2 is red, <0.8 is blue, and anything in the
middle is green?
On Mon, Aug 24, 2020 at 6:28 PM April Ettington
<apriletting...@gmail.com <mailto:apriletting...@gmail.com>> wrote:
Thank you so much!
On Mon, Aug 24, 2020 at 5:33 PM Rui Barradas <ruipbarra...@sapo.pt
<mailto:ruipbarra...@sapo.pt>> wrote:
Hello,
Note that the midpoint argument can make a big difference. In
the code
below try commenting out the line where the default is changed.
f <- function(x){
(x - min(x))/(max(x) - min(x))
}
library(ggplot2)
df1 <- iris[3:5]
names(df1)[1:2] <- c("x", "y")
df1$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
<apriletting...@gmail.com <mailto:apriletting...@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]]
>>
>> ______________________________________________
>> R-help@r-project.org <mailto:R-help@r-project.org> mailing
list -- To UNSUBSCRIBE and more, see
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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.
>
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