How to Add Legend to Geom_Smooth in Ggplot in R

How to add legend to geom_smooth in ggplot in R

Put the colour in aes() and add scale_colour_manual():

ggplot(data = temp, aes(x, y)) + geom_point() + 
  geom_smooth(method = 'lm', formula = y ~ bs(x, df=5, intercept = T), aes(colour="A")) + 
  geom_smooth(method = 'lm', formula = y ~ ns(x, df=2, intercept = T), aes(colour="B")) +
  scale_colour_manual(name="legend", values=c("blue", "red"))

Add a legend to geom_smooth that does not have an aes aesthetic call

Just add another aes mapping in the second geom_smooth() call:

p <- ggplot(mtcars, aes(disp, mpg)) +
     geom_point(aes(color = factor(cyl)), show.legend = FALSE) +
     geom_smooth(aes(color = factor(cyl)), se = FALSE, method = "lm") +
     geom_smooth(se = FALSE, method = "lm", fullrange = TRUE,
                 aes(color = "all data")) +
     scale_color_manual(values = c(scales::hue_pal()(3), "black"))
print(p)

Add legend using geom_point and geom_smooth from different dataset

If you need to label the mean, might need to be a bit creative, because it's not so easy to add legend manually in ggplot.

I simulate something that looks like your data below.

dat1 = data.frame(
       Hour = rep(1:24,each=10),
       value = c(rnorm(60,0,1),rnorm(60,2,1),rnorm(60,1,1),rnorm(60,-1,1))
)
# classify this as raw data
dat1$Data = "Raw"
# calculate mean like you did
dat2 <- dat1 %>% group_by(Hour) %>% summarise(value=mean(value))
# classify this as mean
dat2$Data = "Mean"

# combine the data frames
plotdat <- rbind(dat1,dat2)
# add a dummy variable, we'll use it later
plotdat$line = "Loess-Smooth"

We make the basic dot plot first:

ggplot(plotdat, aes(x = Hour, y = value,col=Data,size=Data)) +
  geom_point() + 
  scale_color_manual(values=c("blue","darkgray"))+
  scale_size_manual(values=c(3,1),guide=FALSE)

Note with the size, we set guide to FALSE so it will not appear. Now we add the loess smooth, one way to introduce the legend is to introduce a linetype, and since there's only one group, you will have just one variable:

ggplot(plotdat, aes(x = Hour, y = value,col=Data,size=Data)) +
  geom_point() + 
  scale_color_manual(values=c("blue","darkgray"))+
  scale_size_manual(values=c(3,1),guide=FALSE)+
  geom_smooth(data=subset(plotdat,Data="Raw"),
  aes(linetype=line),size=1,alpha=0.3,
         method = "loess", span = 0.2, color = "red", fill = "blue")

Changing the legends of plot using geom_smooth in ggplot2

Do you get the error if you run the code like this?

ggplot(mtcars, aes(x=mpg, y=disp, group=group)) +
    geom_smooth(method=lm, se=FALSE,fullrange=TRUE, show.legend=TRUE,aes(linetype=group), colour="black")+
    labs(linetype="Legend")+
    scale_linetype_discrete(labels=c("Experiment", "Control"))

I get this plot:

Mixed fill color in ggplot2 legend using geom_smooth() in R

You can add the fill as an aesthetic mapping, ensuring you name it the same as the color mapping to get legends to merge:

library(ggplot2)

ggplot(data=iris, aes(x=Sepal.Width, y=Sepal.Length)) +
  geom_point(aes(shape = "data")) +
  geom_smooth(method=loess, aes(colour="Loess", fill="Loess")) +
  geom_smooth(method=lm, aes(colour="LM", fill = "LM")) +
  scale_fill_manual(values = c("yellow", "gray"), name = "model")  +
  scale_colour_manual(values = c("red", "blue"), name = "model") +
  labs(shape = "")

How to add multiple geom_smooth lines to the legend (ggplot)?

Your data is in the wide format, or like a matrix. There's no easy way to add a custom legend in ggplot, so you need to transform your current data to a long format. I simulated 3 curves like what you have, and you can see if you call geom_line or geom_smooth with a variable ("name" in the example below) that separates your different values, it will work and produce a legend nicely.

library(dplyr)
library(tidyr)
library(ggplot2)
X = 1:50
#simulate data
Data = data.frame(
       BA=X,
       BAgp1 = log(X)+rnorm(length(X),0,0.3),
       BAgp2 = log(X)+rnorm(length(X),0,0.3) + 0.5,
       BAgp3 = log(X)+rnorm(length(X),0,0.3) + 1)

# convert this to long format, use BA as id
Data <- Data %>% pivot_longer(-BA)
#define colors
COLS = c("red","turquoise","orange")
names(COLS) = c("BAgp1","BAgp2","BAgp3")
###
ggplot(Data) + 
  geom_smooth(aes(BA,value,colour=name,fill=name)) +
  # change name of legend here 
  scale_fill_manual(name="group",values=COLS)+
  scale_color_manual(name="group",values=COLS)

ggplot2: Adding geom_smooth() destroys the point legend

I think it is because size=mean.unemploy is placed globally. If you put it in the aes of ggplot, it would affect whole geom. It means that the new geom_smooth would read the size argument, either.

Since the size is only needed for the geom_point, it is okay to put it in mapping of _point. You might only change that part.

library(tidyverse)
# your dataset
ggplot(econ3, aes(x=decade, y=mean.uempmed),guide=FALSE) + # remove size aesthetic
  geom_point(aes(size=mean.unemploy), colour="blue", fill="lightblue", shape=21) + # size aesthetic in geom_point
  scale_size_area(max_size = 15)+
  geom_smooth(method=lm, se=FALSE, formula = y~x, aes(color="lm"))+
  theme_gray()+
  labs(title = "Unemployment Level per Decade",
       subtitle = "(1967-2015)",
       caption = "Data from the US economic time series.",
       tag = "Figure 3",
       x = "Mean of Median Duration of Unemployment (Weeks)",
       y = "Decade")

If you modify the first two lines, the legend of the points would not be touched.

How to create a linetype legend in ggplot with different dataframes

Bring the line linetype inside aes() and use lab() to give title for the legend.

ggplot() + 
  geom_smooth(data = mydf1, aes(x, predicted, linetype = "Group 1"), method = "lm", colour = "black") +
  geom_smooth(data = mydf2, aes(x, predicted, linetype = "Group 2"), method = "lm", colour = "black") +
  geom_smooth(data = mydf3, aes(x, predicted, linetype = "Group 3"), method = "lm", colour = "black") +
  labs(linetype="Group") +
  theme_classic() 

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