This is a question about the ggplot2 package (author: Hadley Wickham). I have existing ggplot objects with distinct colors (resp shapes, linetype, fill...) that I would like to map to a single color, e.g. black. What is the recommended approach?
Clarification: I have to work with these ggplot objects: I cannot re-make them
A ggplot with variables grouped as factors: this is the plot object p I need to work with
p <- ggplot(mtcars, aes(x = mpg, y = wt, group = factor(cyl), colour = factor(cyl))) +
geom_point(size = 5)
Several approaches I know of:
1. scale_colour_grey hack
p + scale_colour_grey(start = 0, end = 0) + # gives correct, useless legend
guides(color = FALSE)
The shorter p + scale_colour_grey(0,0) does not work, you have to be explicit about start and end.
2. scale_colour_manual with rep() hack
p + scale_colour_manual(values = rep("black",3)) # gives correct, useless legend
The simpler scale_colour_manual(values = "black") does not work. This was probably the most intuitive approach. Having to specify the length of the vector makes it less attractive an approach.
3. geom_point() recalled
p + geom_point(colour = "black") + # gives incorrect legend
guides(color = FALSE)
It is well documented that the following is not allowed:
p + scale_colour_manual(colour = "black")
Error in discrete_scale(aesthetic, "manual", pal, ...) :
unused argument (colour = "black")
Removing the color mapping directly seems to work:
p_bw = p
p_bw$mapping$colour = NULL
gridExtra::grid.arrange(p, p_bw)
If you just want to set the points to black and get rid of the color legend, I think you can just to this:
p + scale_colour_manual(values=rep("black",length(unique(mtcars$cyl))),
guide=FALSE)
Related
I'm trying to use ggplot2 to make some sort of timeline using values from a dataframe (df). I've managed to plot the data exactly how I want it (the different colored line segments connecting the x-marks in this exact order, i.e., from left to right: 'early', 'unknown', 'late', 'sub'). The startpoint and endpoint columns in the dataframe are used to define the positions of the points and line segments.
The problem is that the legend doesn't show the color of the 'x' icons, they are just grey. I've tried adding scale_color_manual() and scale_fill_manual() commands but they don't seem to change anything. The legend does display the correct color when I change the shape to shape = 21, however, I really want the shape to be 4 (x icons). I don't care about the shape of the legend though but scale_shape_manual() again didn't change anything about the legend.
I have also tried placing different color arguments inside and outside the aes() argument of ggplot(), geom_segment() and/or geom_point().
How can I make the icons from the legend show the correct color?
Below I added a piece of code to reproduce the problem.
library(ggplot2)
library(RColorBrewer)
## Define dataframe
df <- data.frame(Var = c("sub","late","unknown","early"),
Time = c(10,267,0,1256),
Endpoint = c(1533,1523,1256,1256),
Startpoint = c(1523,1256,1256,0))
colorscheme <- RColorBrewer::brewer.pal(9, "Set1")[c(1,4,2,3)]
## Make plot
ggplot(df, aes(x="", y=Endpoint, fill=Var), color =colorscheme) +
geom_segment( aes(x="", xend="", y=Startpoint, yend=Endpoint), color = colorscheme) +
geom_point(aes(x="", y=Endpoint),size=5, shape=4 , color = colorscheme) +
coord_flip()
Thanks in advance for any suggestions!
You should use color instead of fill. To remove the line from the legend, use guides(color = guide_legend(override.aes = list(linetype = 0))) or use show.legend = F in geom_segment.
Also, arguments passed in ggplot need not to be repeated afterward.
ggplot(df, aes(x="", y=Endpoint, color=Var), colorscheme) +
geom_segment(aes(xend="", y=Startpoint, yend=Endpoint)) +
geom_point(size=5, shape=4) +
coord_flip() +
guides(color = guide_legend(override.aes = list(linetype = 0)))
#or
ggplot(df, aes(x="", y=Endpoint, color=Var), colorscheme) +
geom_segment(aes(xend="", y=Startpoint, yend=Endpoint)) +
geom_point(size=5, shape=4) +
coord_flip()
Try this:
ggplot(df, aes(x = "", y = Endpoint, color = Var), colorscheme) +
geom_segment(aes(x = "", xend = "", y = Startpoint, yend = Endpoint), show.legend = FALSE) +
geom_point(aes(x = "", y = Endpoint), size = 5, shape = 4) +
coord_flip()
In this way legend will show only X
I need to create one-row heatmap, that occasionally will be derived from NA-only column, but has to be displayed anyway. In the example below generating heatmap from p2 column will render "Error: Must request at least one colour from a hue palette.". Is there any way to force ggplot to display an "empty" heatmap?
library(ggplot2)
id <- letters[1:5]
p1 <- factor(c(1,NA,2,NA,3))
p2 <- factor(c(NA,NA,NA,NA,NA))
dat <- data.frame(id=id, p1=p1, p2=p2)
ggplot(dat, aes(x=id,y="identity")) + geom_tile(aes(fill = p1), colour = "white") #works fine
ggplot(dat, aes(x=id,y="identity")) + geom_tile(aes(fill = p2), colour = "white") #renders error
I think if you explicitly tell ggplot how to handle NA values using the na.value inside a scale_fill_manual call. This should take care of your issue, or at least head you in the right direction:
ggplot(dat, aes(x=id,y="identity")) +
geom_tile(aes(fill = p2), colour = "white") +
scale_fill_manual(values = "white",
na.value = "black")
You can change the values argument to better handle the colors you like
I am trying to create a legend in ggplot2 for hlines and ablines using clues from other similar questions. I am close to getting what I need with the following code (and example image) but I can't seem to get rid of the extra lines crossing the legend icons.
p <- ggplot(mtcars, aes(x = wt, y=mpg, col = factor(cyl))) + geom_point()
p + geom_hline(aes(lty="foo",yintercept=20)) +
geom_hline(aes(lty="bar",yintercept=25)) +
geom_hline(aes(lty="bar",yintercept=30)) +
geom_abline(aes(lty = "regression", intercept = 10 , slope = 1)) +
scale_linetype_manual(name="",values=c(2,3,1))
This behavior in the legend only appears when I include the abline. Without it, both hline appear as intended in the legend.
What am I missing here?
As a secondary point: both hlines (labelled "bar" here) here use the exact same configuration, but have different values for yintercept. I wasn't able to draw both of them with the same command, receiving an error (Error: Aesthetics must be either length 1 or the same as the data (32): linetype, yintercept).
Whenever I copy&paste a command like this, it feels like I'm not doing it right. Is it possible to set two yintercepts, while manually defining the linetype to create a legend?
You can use argument show.legend in the geom_abline:
ggplot() +
geom_point(aes(x = mtcars$wt, y=mtcars$mpg, col = factor(mtcars$cyl))) +
geom_hline(aes(lty=c("foo", "bar","bar"),yintercept=c(20,25,30))) +
geom_abline(aes(lty = "regression", intercept = 10 , slope = 1), show.legend = F) +
scale_linetype_manual(name="",values=c(2,3,1) )
If you not define the data on the ggplot command you can define all the hlines in just one command:
ggplot(mtcars, aes(x = wt, y=mpg, col = factor(cyl))) + geom_point() +
geom_hline(aes(lty="foo",yintercept=20)) +
geom_hline(aes(lty="bar",yintercept=25)) +
geom_hline(aes(lty="bar",yintercept=30)) +
geom_abline(aes(lty = "regression", intercept = 10 , slope = 1), show.legend = F) +
scale_linetype_manual(name="",values=c(2,3,1) )
I am an absolute beginner in ggplot2. I got frustrated with ggplot2 and started reading Wickham's awesome book. He says that "a scale is required for every aesthetic used on the plot.".
So, I did the following:
Try 1:
huron <- data.frame(year = 1875:1972, level = as.numeric(LakeHuron))
ggplot(huron, aes(year)) +
geom_line(aes(y = level + 5, color = "y+5")) +
scale_color_manual(values = c("orange")) +
geom_line(aes(y = level - 5, color = "y-5")) +
scale_color_manual(values = "blue")
Upon running this, I get an error saying " insufficient value of colors provided."
I googled this and found the following thread on SO : ggplot2 Error: Insufficient values in manual scale. In original post, it makes sense why he/she added extra colors. However, I am not sure why this would be the case in my example because I have two layers, each with its own aesthetic.
Try 2
This code will work: (as in I can see two line plots in two different color and a legend--this is my objective)
ggplot(huron, aes(year)) +
geom_line(aes(y = level + 5, color = "y+5")) +
scale_color_manual(values = c("orange", "blue")) + #Added another color here.
geom_line(aes(y = level - 5, color = "y-5"))
Surprisingly, the above code shows something weird--I have got two aesthetics and only one scale.
Question 1: This is quite surprising because as we can see that there are two geoms but only one scale. Correct? I know Wickham cannot be wrong. So, what am I missing?
Question 2: Also, out of curiosity, if I have multiple geoms each with one aesthetic as in above case, and with one scale tied to each, how will ggplot know which scale ties back to which geom? As in, how would ggplot2 know whether layer1 goes with scale with color = red and layer2 goes with color = blue?
I'd sincerely appreciate your thoughts. Thanks in advance.
To answer the specific question in the comments:
If you want to force specific colors, you need to use scale_color_manual. As the name suggests, this needs some manual work.
library(ggplot2)
#default colors
#http://stackoverflow.com/a/8197703/1412059
gg_color_hue <- function(n) {
hues = seq(15, 375, length = n + 1)
hcl(h = hues, l = 65, c = 100)[1:n]
}
ggplot(mpg, aes(displ, hwy)) +
geom_point(aes(colour = class)) +
geom_smooth(method = "lm", se = FALSE, aes(color = "model")) +
scale_color_manual(values = setNames(c(gg_color_hue(length(unique(mpg$class))), "red"),
c(unique(mpg$class), "model")))
However, I would use an additional aesthetic for the line type.
ggplot(mpg, aes(displ, hwy)) +
geom_point(aes(colour = class)) +
geom_smooth(method = "lm", se = FALSE, aes(linetype = "model"), color = "red")
Suppose I have a ggplot with more than one legend.
mov <- subset(movies, length != "")
(p0 <- ggplot(mov, aes(year, rating, colour = length, shape = mpaa)) +
geom_point()
)
I can turn off the display of all the legends like this:
(p1 <- p0 + theme(legend.position = "none"))
Passing show_guide = FALSE to geom_point (as per this question) turns off the shape legend.
(p2 <- ggplot(mov, aes(year, rating, colour = length, shape = mpaa)) +
geom_point(show_guide = FALSE)
)
But what if I want to turn off the colour legend instead? There doesn't seem to be a way of telling show_guide which legend to apply its behaviour to. And there is no show_guide argument for scales or aesthetics.
(p3 <- ggplot(mov, aes(year, rating, colour = length, shape = mpaa)) +
scale_colour_discrete(show_guide = FALSE) +
geom_point()
)
# Error in discrete_scale
(p4 <- ggplot(mov, aes(year, rating, shape = mpaa)) +
aes(colour = length, show_guide = FALSE) +
geom_point()
)
#draws both legends
This question suggests that the modern (since ggplot2 v0.9.2) way of controlling legends is with the guides function.
I want to be able to do something like
p0 + guides(
colour = guide_legend(show = FALSE)
)
but guide_legend doesn't have a show argument.
How do I specify which legends get displayed?
You can use guide = "none" in scale_..._...() to suppress legend.
For your example you should use scale_colour_continuous() because length is continuous variable (not discrete).
(p3 <- ggplot(mov, aes(year, rating, colour = length, shape = mpaa)) +
scale_colour_continuous(guide = "none") +
geom_point()
)
Or using function guides() you should set "none" for that element/aesthetic that you don't want to appear as legend, for example, fill, shape, colour.
p0 <- ggplot(mov, aes(year, rating, colour = length, shape = mpaa)) +
geom_point()
p0+guides(colour = "none")
UPDATE
Both provided solutions work in new ggplot2 version 3.3.5 but movies dataset is no longer present in this library. Instead you have to use new package ggplot2movies to check those solutions.
library(ggplot2movies)
data(movies)
mov <- subset(movies, length != "")
You can simply add show.legend=FALSE to geom to suppress the corresponding legend