[R] ggplot two-factor legend

Jeff Newmiller
Thu, 18 Jul 2024 16:12:54 -0000

If I follow your question, you want redundant aesthetics. Ggplot normally
notices correlated aesthetic mapping variables and merges the legends, so the
most likely answer is that your data are not fully correlated in all rows. I
have also seen this where data are drawn from different dataframes for different
layers since it is hard to merge factors, but I don't see that here.

You are using the group parameter... try removing that? The group parameter
overrides the automatic group determination. There might be a syntax for
specifying correlated grouping, but I don't know it... I normally just
verify that my data meets the requirements to be automatically identified as
correlated if that is my goal, since that is a prerequisite anyway.

On July 18, 2024 8:27:05 AM PDT, "SIBYLLE ST?CKLI via R-help"
<r-help at r-project.org> wrote:
>Hi
>
>I am using ggplot to visualise y for a two-factorial group (Bio: 0 and 1) x
>= 6 years. I was able to adapt the colour of the lines (green and red) and
>the linetype (solid and dashed).
>Challenge: my code produces now two legends. One with the colors for the
>group and one with the linetype for the group. Does somebody have a hint how
>to adapt the code to produce one legend? Group 0 = red and dashed, Group 1
>green and solid?
>
>
>MS1<- MS %>% filter(QI_A!="NA") %>% droplevels()
>dev.new(width=4, height=2.75)
>par(mar = c(0,6,0,0))
>p1<-ggplot(data = MS1, aes(x= Jahr, y= QI_A,group=Bio,color=Bio,
>linetype=Bio)) +
>    	geom_smooth(aes(fill=Bio) , method = "lm" , formula = y ~ x +
>I(x^2),linewidth=1) +
>	theme(panel.background = element_blank())+
>	theme(axis.line = element_line(colour = "black"))+
>  theme(axis.text=element_text(size=18))+
>  theme(axis.title=element_text(size=20))+
>	ylab("Anteil BFF an LN [%]") +xlab("Jahr")+
>	scale_color_manual(values=c("red","dark green"),
labels=c("?LN",
>"BIO"))+
>	scale_fill_manual(values=c("red","dark green"), labels=
c("?LN",
>"BIO"))+
>	theme(legend.title = element_blank())+
>  theme(legend.text=element_text(size=20))+
>  scale_linetype_manual(values=c("dashed", "solid"))
>p1<-p1 + expand_limits(y=c(0, 30))
>
>kind regards
>Sibylle
>
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Sent from my phone. Please excuse my brevity.