Removing the border of legend symbol - r

Question

I was trying to plot some predicted vs. actual data, something that resembles the following:
# Some random data
x <- seq(1: 10)
y_pred <- runif(10, min = -10, max = 10)
y_obs <- y_pred + rnorm(10)
# Faking a CI
Lo.95 <- y_pred - 1.96
Hi.95 <- y_pred + 1.96
my_df <- data.frame(x, y_pred, y_obs, Lo.95, Hi.95)
ggplot(my_df, aes(x = x, y = y_pred)) +
geom_line(aes(colour = "Forecasted Data"), size = 1.2) +
geom_point(aes(x = x, y = y_obs, colour = "Actual Data"), size = 3) +
geom_ribbon(aes(ymin=Lo.95, ymax=Hi.95, x=x, linetype = NA, colour = "Confidence Interval"), alpha=0.2) +
theme_grey() +
scale_colour_manual(
values = c("gray30", "blue", "red"),
guide = guide_legend(override.aes = list(
border=c(NA, NA, NA),
fill=c("gray30", "white", "white"),
linetype = c("blank", "blank", "solid"),
shape = c(NA, 19, NA))))
The plot looks like this:
The only issue I have with this plot is the red border surrounding the legend item symbol for the line (i.e. the forecasted data). Is there any way I can remove it without breaking the rest of my plot?

Answer 1

I think geom_ribbon was the problem. If we take its color & fill out of aes, everything looks fine
library(ggplot2)
# Some random data
x <- seq(1: 10)
y_pred <- runif(10, min = -10, max = 10)
y_obs <- y_pred + rnorm(10)
# Faking a CI
Lo.95 <- y_pred - 1.96
Hi.95 <- y_pred + 1.96
my_df <- data.frame(x, y_pred, y_obs, Lo.95, Hi.95)
m1 <- ggplot(my_df, aes(x = x, y = y_pred)) +
geom_point(aes(x = x, y = y_obs, colour = "Actual"), size = 3) +
geom_line(aes(colour = "Forecasted"), size = 1.2) +
geom_ribbon(aes(x = x, ymin = Lo.95, ymax = Hi.95),
fill = "grey30", alpha = 0.2) +
scale_color_manual("Legend",
values = c("blue", "red"),
labels = c("Actual", "Forecasted")) +
guides( color = guide_legend(
order = 1,
override.aes = list(
color = c("blue", "red"),
fill = c("white", "white"),
linetype = c("blank", "solid"),
shape = c(19, NA)))) +
theme_bw() +
# remove legend key border color & background
theme(legend.key = element_rect(colour = NA, fill = NA),
legend.box.background = element_blank())
m1
As we leave Confidence Interval out of aes, we no longer have its legend. One workaround is to create an invisible point and take one unused geom to manually create a legend key. Here we can use size/shape (credit to this answer)
m2 <- m1 +
geom_point(aes(x = x, y = y_obs, size = "Confidence Interval", shape = NA)) +
guides(size = guide_legend(NULL,
order = 2,
override.aes = list(shape = 15,
color = "lightgrey",
size = 6))) +
# Move legends closer to each other
theme(legend.title = element_blank(),
legend.justification = "center",
legend.spacing.y = unit(0.05, "cm"),
legend.margin = margin(0, 0, 0, 0),
legend.box.margin = margin(0, 0, 0, 0))
m2
Created on 2018-03-19 by the reprex package (v0.2.0).

Answer 2

A better way to address this question would be to specify show.legend = F option in the geom_ribbon(). This will eliminate the need for the second step for adding and merging the legend key for the confidence interval. Here is the code with slight modifications.
ggplot(my_dff, aes(x = x, y = y_pred)) +
geom_line(aes(colour = "Forecasted Data"), size = 1) +
geom_point(aes(x = x, y = y_obs, colour = "Actual Data"), size = 1) +
geom_ribbon(aes(ymin=Lo.95, ymax=Hi.95, x=x, linetype = NA, colour = "Confidence Interval"), alpha=0.2, show.legend = F) +
theme_grey() +
scale_colour_manual(
values = c("blue", "gray30", "red"))+
guides(color = guide_legend(
override.aes = list(linetype = c(1, 1, 0)),
shape = c(1, NA, NA),
reverse = T))
My plot
Credit to https://stackoverflow.com/users/4282026/marblo
for their answer to similar question.