ggplot legend labels and colors - r

Question

I am struggling with ggplot to produce the legend of this figure. For now, I am only doing for one map, when it works I'l produce the four maps in the same plot.
I would like a legend like this: bottom, title in the center and above the scale, labels and colors, and omit the NA values.
Here is my code:
Reading the shapefile and installing a new variable
map_ev#data$id = rownames(map_ev#data)
map_ev.points = fortify(map_ev, region="id")
map_ev.df = join(map_ev.points, map_ev#data, by="id")
map_ev.df$median_norm = map_ev.df$median / map_ev.df$VOM
Vector with theme opts for ggplot
theme_opts <- list(theme(panel.grid.minor = element_blank(),
panel.grid.major = element_blank(),
panel.background = element_blank(),
panel.border = element_blank(),
axis.line = element_blank(),
axis.text.x = element_blank(),
axis.text.y = element_blank(),
axis.ticks = element_blank(),
axis.title.x = element_blank(),
axis.title.y = element_blank(),
plot.title = element_text(size=12, hjust=0.5),
legend.position = "bottom",
legend.title=element_blank()))
Installing the variable breaks
map_ev.df$median_norm <- cut(map_ev.df$median_norm, breaks=c(-200, -100, -50, -20, -5, 0, 5, 20, 50, 100, +200))
Checking the breaks
levels(map_ev.df$median_norm)
Colors to be used
color_map <- palette(c("#5b2e07", "#904d07", "#b98436", "#dfc27e", "#f6e8c3",
"#c9e9e4", "#84cdc4", "#3c958f", "#01675a", "#073a31"))
ggplot code
ggplot(map_ev.df) +
aes(long,lat,group=group,fill=median_norm, color=median_norm) +
geom_polygon() + geom_path(color="black") +
labs(title="Equivalent variation") + coord_equal() +
theme_opts
For now I am getting this figure:
Thanks all, I appreciate your help!

Answer 1

I just noticed you wanted manual colours for the fill. You can use:
myscale <- c("(-1,10]"="#BBDF27", "(10,20]"="#43BF71", "(20,30]"="#21908C", "(30,50]"="#35608D", "(50,101]"="#482576", "(101,300]"="#ffeeed")
combined with:
scale_fill_manual(values=myscale,na.value="#e0e0e0",name="",labels=c("<10","10 - 20","20 - 30","30 - 50", ">50","Estimate", "NA"))
where scale_fill manual replaces scale_fill_brewer in the other answer.
Just replace the colour and label values with your own. The values that need to go into myscale are shown when you plot your map without any labels. Good luck!

Answer 2

The reason you don't have a title, is because you never specified one, and if you did, you're deleting it again by writing legend.title=element_blank() in theme. Instead I rewrote it to specify the title should be centered. Using guides(colour = guide_legend(title.position = "top"),fill = guide_legend(title.position = "top",nrow=1,byrow=TRUE)) I set the position to "top" and made sure it will only be one row of legend items. (I left colour= here in case you do need it).
You also seem to want black borders, this means I deleted all colour= since that specifies the colour of the borders.
I've added a scale_fill_brewer, there are more color palettes available. Within this you can specify your legend title and the appearance of your legend labels. These need to be manually adjusted every time you change your input data, by the way.
I don't know how to remove the legend item for NA, sorry.
This is the total code I came up with:
ggplot(map_ev.df) +
aes(long,lat,group=group,fill=median_norm) +
scale_fill_brewer(palette="BrBG",name= "Title of legend",labels=c("-200 - -100","-100 - 50","-5 - 0","0 - 5", "label for NA"))+
geom_polygon() + geom_path(color="black") +
labs(title="Equivalent variation") + coord_equal() +
theme(panel.grid.minor = element_blank(),
panel.grid.major = element_blank(),
panel.background = element_blank(),
panel.border = element_blank(),
axis.line = element_blank(),
axis.text.x = element_blank(),
axis.text.y = element_blank(),
axis.ticks = element_blank(),
axis.title.x = element_blank(),
axis.title.y = element_blank(),
plot.title = element_text(size=12, hjust=0.5),
legend.position = "bottom",
legend.direction = "horizontal",
legend.title = element_text(hjust=0.5))+
guides(colour = guide_legend(title.position = "top"),fill = guide_legend(title.position = "top",nrow=1,byrow=TRUE))
Using some data of my own for the fill:
map