Add Both Legends to a Plot

Question

I have a plot that I have made counting the number of genes over a period of time in two samples. I would like to plot both sets of numbers in a waterfall chart. I am able to get the chart but I have difficulty getting both legends to show up. I have the following tables:

    genotype   time degs
1         S  1 dpi   91
2         S  7 dpi  121
3         S 14 dpi  102
4         S 22 dpi  349
9         R  1 dpi  186
10        R  7 dpi  220
11        R 14 dpi  236
12        R 22 dpi  404

    genotype   time degs
5         S  1 dpi  -99
6         S  7 dpi -120
7         S 14 dpi -157
8         S 22 dpi -860
13        R  1 dpi -121
14        R  7 dpi -122
15        R 14 dpi -161
16        R 22 dpi -288

I am using the following code to make the plot:

deg.dn$degs=deg.dn$degs*-1
deg.up$time=as.character(deg.up$time)
deg.dn$time=as.character(deg.dn$time)
deg.up$time = factor(deg.up$time, levels=unique(deg.up$time))
deg.dn$time = factor(deg.dn$time, levels=unique(deg.dn$time))
deg.up$genotype=as.character(deg.up$genotype)
deg.dn$genotype=as.character(deg.dn$genotype)
deg.dn$genotype = factor(deg.dn$genotype, levels=unique(deg.dn$genotype))
deg.up$genotype = factor(deg.up$genotype, levels=unique(deg.up$genotype))
breaksup = levels(deg.up$time)
breaksdn = levels(deg.dn$time)
brewup = c("#FEE5D9", "#FCAE91", "#FB6A4A", "#CB181D")
brewdn = c("#EFF3FF", "#BDD7E7", "#6BAED6", "#2171B5")

ggplot() +
  geom_bar(data = deg.up, aes(x=genotype, y=degs, fill=time), stat="identity", position="dodge") +
  scale_fill_manual(values=brewup, breaks=breaksup) +
  new_scale_fill() +
  geom_bar(data = deg.dn, aes(x=genotype, y=degs, fill=time), stat="identity", position="dodge") +
  scale_fill_manual(values=brewdn, breaks=breaksdn)

breaksup and breaksdn are the time columns in the data frames as unique characters.

Would anybody be able to help me get both legends next to each other in the final plot? Thank you.

Plot I Constructed

score 0 · Accepted Answer · answered Sep 05 '20 at 10:14

Here are two ways to put legends next to each other.

The first one just adds the first legend and order them horizontaly. For including both legends, specify the title of each legend in scale_fill_manual. If both legends get the same title, you may speficy the order of the legends. At least to put legends next to each other set legend.box in theme to horizontal.


ggplot() +
  geom_bar(data = deg.up, aes(x=genotype, y=degs, fill=time), stat="identity", position="dodge") +
  scale_fill_manual(values=brewup, 
                    breaks=breaksup, 
                    name = "time",
                    guide = guide_legend(order = 1)) +
  new_scale_fill() +
  geom_bar(data = deg.dn, aes(x=genotype, y=degs, fill=time), stat="identity", position="dodge") +
  scale_fill_manual(values=brewdn, 
                    breaks=breaksdn, 
                    name ="time", 
                    guide = guide_legend(order = 2)) +
  theme(legend.box = "horizontal")

The second apprach is more experimental. In your example your time legends have the same factors (1,7,14,22), so you might push the legends together. I achied this by removing the first legends labels, the second legends title and changed the margins in theme.

ggplot() +
  geom_bar(data = deg.up, aes(x=genotype, y=degs, fill=time), stat="identity", position="dodge") +
  scale_fill_manual(values=brewup, breaks=breaksup, 
                    guide = guide_legend(label = FALSE, 
                                         title = "time", 
                                         order = 1)) +
  new_scale_fill() +
  geom_bar(data = deg.dn, aes(x=genotype, y=degs, fill=time), stat="identity", position="dodge") +
  scale_fill_manual(values=brewdn, 
                    breaks=breaksdn, 
                    guide = guide_legend(title = "",
                    order = 2)) +
  theme(legend.box =  "horizontal",
        legend.margin = margin(0,0,0,-.6, "cm"),
        legend.box.margin =  margin(0,1,0,1, "cm"))

Thanks. That seems to work but when I try it with theme_bw, both legend elements fall back to separate rows. I there a piece of code in theme_bw I should be using? — Patrick Thomas, Sep 07 '20 at 04:09
theme_bw() needs to be above theme(), overwise theme_bw() will override the legend position. .... + theme_bw() + theme(legend.box = "horizontal") — tamtam, Sep 07 '20 at 06:48

Add Both Legends to a Plot

1 Answers1