Problem with key in ggplot, using double axis y + geom_line()+geom_point() x geom_bar()

Question

Hello, I have another problem regarding the presentation of legend, in this case, using axis y double (ggplot::scale_y_continuous::sec_axis), and geom_line()+geom_point() x geom_bar(), as shown in figure 1. I would like to present the legend as a square without line and colored point, identifying "UR" and 3 squares, with the captions for "Tmáx", "Tméd" and "Tmín", with their respective shape, linetype, and colour.

Note: I am using the package extrafont, to the "Times New Roman".

Code:

library(ggplot2)
library(extrafont)

novo<-structure(list(AVA=c(1L,2L,3L,4L,5L,6L,7L,8L,9L,10L,
11L,12L,1L,2L,3L,4L,5L,6L,7L,8L,9L,10L,11L,12L,
1L,2L,3L,4L,5L,6L,7L,8L,9L,10L,11L,12L),variable=structure(c(1L,
1L,1L,1L,1L,1L,1L,1L,1L,1L,1L,1L,2L,2L,2L,2L,2L,
2L,2L,2L,2L,2L,2L,2L,3L,3L,3L,3L,3L,3L,3L,3L,3L,
3L,3L,3L),.Label=c("Tar","Tarmin","Tarmax"),class="factor"),
value=c(26.9102916666667,26.0853333333333,27.8317291666667,
28.3282083333333,27.4253958333333,30.3683196875,25.3293125,
26.888375,22.8657708333333,26.8046458333333,23.222375,
23.4121041666667,22.08,21.887,25.673,23.925,23.861,
25.705,20.45,21.919,17.265,21.49,19.581,18.251,32.012,
31.057,31.089,32.762,32.001,34.997005,30.542,31.851,
27.85,32.516,27.518,28.612)),row.names=c(NA,-36L),class="data.frame")

UR<-structure(list(AVA=1:12,variable=structure(c(1L,1L,1L,
1L,1L,1L,1L,1L,1L,1L,1L,1L),.Label="UR",class="factor"),
value=c(74.4006458333333,74.8331458333333,78.3165833333333,
73.8219375,78.0607708333333,68.2176286458333,69.2232916666667,
67.881625,64.4237916666667,64.3282083333333,66.3142916666667,
70.0928125)),row.names=c(NA,-12L),class="data.frame")

ggplot(novo,aes(x=AVA,y=value,group=variable,colour=variable))+geom_point(aes(shape=variable),cex=1.5)+geom_line(aes(linetype=variable),cex=1.2)+
  scale_y_continuous(name = expression("Temperatura do ar("^"o"*"C )"),limits=c(0,40),
                     sec.axis = sec_axis(~ . *2,name=expression("Umidade relativa do ar (%)")))+
  geom_bar(data=UR,aes(x=AVA,y=value/2,colour=variable),alpha=.2,stat="identity",width = .25)+
  scale_shape_manual("",breaks=c("Tar","Tarmax","Tarmin","UR"),values=c(15,16,18),labels=c("Tméd","Tmáx","Tmín","UR ar"))+
  scale_linetype_manual("",breaks=c("Tar","Tarmax","Tarmin","UR"),values=c(1,2,4),labels=c("Tméd","Tmáx","Tmín","UR ar"))+
  scale_fill_manual("",breaks=c("Tar","Tarmax","Tarmin","UR"),values=c("purple"),labels=c("Tméd","Tmáx","Tmín","UR ar"))+
  scale_colour_manual("",labels=c("Tméd","Tmáx","Tmín","UR ar"),breaks=c("Tar","Tarmax","Tarmin","UR"),values=c("black","red","blue","purple"))+
  theme(panel.background = element_rect(fill=NA),
        panel.border = element_rect(fill=NA),
        axis.title.y = element_text(size = rel(1.5), angle = 90),text=element_text(family="Times New Roman", face="bold", size=12),
        legend.text = element_text(size=12,face = "bold"),
        axis.text = element_text(size=12,face="bold"),
        legend.position = "bottom")

Answer 1

You’re defining color and group in global aesthetics, which will make them apply to all geometries. Put in the global the parameters that apply to all and the aesthetics of the geometries what applies only to each one of them. The same goes for scales.

labs <- c("Temperatura", labels = c("média", "mínima", "máxima"))

ggplot(novo,aes(AVA, value)) +
  geom_col(data = UR, aes(y = value/2, fill = variable), colour = "black", alpha=.3, width = .25) +
  geom_point(aes(shape = variable, colour = variable), cex = 1.5) +
  geom_line(aes(linetype = variable, colour = variable), cex = 1) +
  scale_fill_manual(NULL, values = "#6baed6") +
  scale_color_manual(labs, values = c("black", "blue", "red")) +
  scale_shape_manual(labs, values = c(15, 16, 18)) +
  scale_linetype_manual(labs, values = c(1, 2, 4)) +
  scale_y_continuous("Temperatura (ºC)", sec.axis = sec_axis(~.*2, "Umidade relativa (%)"))

I removed the theme for easy playback. Some notes:

• geom_col is the shortcut for using bars with stat = identity
• bar, color represents the color of the outer line, use fill for the color of the bar itself
• geometries are plotted in order; place geom_col first if you want her in the background.
• use NULL instead of "" in captions titles; this corresponds to using element_blank
• colors, formats, etc that will be displayed in vain caption inside the aes() and the personalization goes on scale_* corresponding. Those that do not vary and will not be displayed in legend go outside the aes