ggplot2 Adding data labels to grouped histograms chart - r

Question

I have a table called "year" looking like this:
# Year Stars n pct
1 2015 1 778 26.5
2 2015 2 247 8.4
3 2015 3 286 9.7
4 2015 4 439 15
5 2015 5 1186 40.4
6 2016 1 678 22.7
7 2016 2 233 7.8
8 2016 3 256 8.6
9 2016 4 451 15.1
10 2016 5 1372 45.9
11 2017 1 501 24.3
12 2017 2 180 8.7
13 2017 3 215 10.4
14 2017 4 274 13.3
15 2017 5 894 43.3
16 2018 1 391 25.1
17 2018 2 125 8
18 2018 3 144 9.3
19 2018 4 196 12.6
20 2018 5 699 45
21 2019 1 474 22.4
22 2019 2 124 5.9
23 2019 3 168 8
24 2019 4 277 13.1
25 2019 5 1070 50.6
26 2020 1 148 25.3
27 2020 2 50 8.5
28 2020 3 64 10.9
29 2020 4 77 13.1
30 2020 5 247 42.2
Data represents have users have rated app from google play store through years. They rate it by giving 1 (bad) to 5 (great) stars.
I'm trying to make a chart which shows share of stars by star level and year using this code:
ggplot(year, aes(as.factor(Stars), pct)) +
geom_bar(aes(fill = as.factor(Year)), position = "dodge", stat="identity") +
scale_fill_manual(values=c("#05668D", "#028090", "#00A896", "#02C39A", "#4ecdc4", "#F0F3BD")) +
ylab("Share of stars (in %)") +
xlab("Stars") +
geom_text(label=round(year$pct, digits = 1),
position=position_dodge(0.9),
size = 4, fontface = "bold") +
ylim(0,50) +
theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank(),
panel.background = element_blank(), axis.line = element_line(colour = "black"),
plot.title = element_text(hjust = 0.5)) +
ggtitle("Share of stars")
Unfortunately, I get two problems:
1) For some reason I get the following warning message:
Warning messages:
1: Removed 1 rows containing missing values (geom_bar).
2: Removed 1 rows containing missing values (geom_text).
Meaning that data for 2020, 4 stars is missing though it should 13.1
2) My labels are all over the place while I would like them to be positioned above the corresponding column on the chart.
Could someone please help me with this problems?

Answer 1

You need to set the grouping correctly for the dodging to work. Instead of using ylim, which cuts off one of your bars, we can turn off axis expansion which looks better for bars going down to 0. (You may need to use ylim with a higher value to make sure all labels are printed.)
ggplot(year, aes(as.factor(Stars), pct)) +
geom_col(aes(fill = as.factor(Year)), position = "dodge") +
geom_text(
aes(label = round(pct, digits = 1), group = interaction(Stars, Year)),
position = position_dodge(0.9), size = 3, fontface = "bold", vjust = 0
) +
scale_fill_manual(values=c("#05668D", "#028090", "#00A896", "#02C39A", "#4ecdc4", "#F0F3BD")) +
scale_y_continuous(expand = c(0, 0)) +
theme(
panel.grid.major = element_blank(), panel.grid.minor = element_blank(),
panel.background = element_blank(), axis.line = element_line(colour = "black"),
plot.title = element_text(hjust = 0.5)
) +
labs(title = "Share of stars", x = "Share of stars (in %)", y = "Stars", fill = "Year")

Answer 2

Problem #1: You're getting that message because row #25 has a pct value of 50.6, and you're setting the maximum limit on the y-axis to 50.
Problem #2: Using position_dodge2 in your geom_text will make the labels line up, and I think adding a little space above the bar makes it more readable so I also added vjust = -1
ggplot(year, aes(as.factor(Stars), pct)) +
geom_bar(aes(fill = as.factor(Year)), position = "dodge", stat="identity") +
scale_fill_manual(values=c("#05668D", "#028090", "#00A896", "#02C39A", "#4ecdc4", "#F0F3BD")) +
ylab("Share of stars (in %)") +
xlab("Stars") +
geom_text(label=round(year$pct, digits = 1),
position=position_dodge2(width = .9),
vjust = -1,
fontface = "bold",
size = 4) +
ylim(0,50) +
theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank(),
panel.background = element_blank(), axis.line = element_line(colour = "black"),
plot.title = element_text(hjust = 0.5)) +
ggtitle("Share of stars")

Answer 3

Simply use position_dodge2 to fix the labels and get rid of the ylim to show all data:
library(ggplot2)
ggplot(year, aes(as.factor(Stars), pct)) +
geom_bar(aes(fill = as.factor(Year)), position = "dodge", stat="identity") +
scale_fill_manual(values=c("#05668D", "#028090", "#00A896", "#02C39A", "#4ecdc4", "#F0F3BD")) +
ylab("Share of stars (in %)") +
xlab("Stars") +
geom_text(aes(label=round(pct, digits = 1)),
position=position_dodge2(0.9),
size = 4, fontface = "bold") +
theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank(),
panel.background = element_blank(), axis.line = element_line(colour = "black"),
plot.title = element_text(hjust = 0.5)) +
ggtitle("Share of stars")