Match legend text labels with their correct fill colors in barplot

Question

I am plotting a table with the values below:

No	Sector	Amount USD (million)
1	Air Pollution	134
2	Water Resources	3,158
3	Land Use and Land Use Change	91
4	Biodiversity	74
5	Agriculture	2,386
6	Industry and Commerce	528
7	Mining	312
8	Tourism	252
9	Energy	262
10	Transport	1,071
11	Disaster Risk Management and Human Settlements	519
12	Waste Management	231
13	Health	52
14	Gender; People Living With HIV and AIDS and other Vulnerable groups	25
15	Children and Youth	32
16	Capacity Building	45
17	Role of Meteorological Services	23
18	Technology Transfer	574
19	Climate Change Education	15
20	Public Awareness	15
21	Climate Change Governance	88

Once done, I put in the following code in R studio

#reading the table into R studio
zim5 <- read_excel ('zimbabwe-climate-finance-excel4.xlsx', col_names = TRUE)
zim5

#creating the objects for easier typing
sector1 <- zim5$Sector
sector1
millions1 <- zim5$'Amount USD (million)'
millions1

#finally plotting the barplot with a legend
mycol <- colors()[444:500]
barplot(millions1~sector1, width = 4, space = 0.2, main = 'Zimbabwe budget by sector', xlab = 'Economic sectors', ylab = 'Amount in US $ millions', 
        col = mycol, cex.names = 0.6, horiz = F, las = 2)
legend('top', sector1, fill = mycol, cex = 0.7, text.font = 3)

My aim was to get a barplot with a legend. However, although I managed to create the barplot (including a different one with horizontal bars (horiz = T and las = 1), my legend always seems to display the text labels in a different order than in the barplot in both. i.e., Air pollution corresponds with the fill of Agriculture in the graphic and so on.

Though I noticed R studio seems to balance out the position of the bars according to their heights or something, I want the legend labels to correspond with their appropriate fill colours like in the x axis of the plot, whether or not R studio orders the bars differently from the table.

user_8206434 · Answer

Here it is - turning the label into a factor solves the problem.

z <- structure(list(no = 1:21, sector = c("Air Pollution", "Water Resources", 
                                          "Land Use and Land Use Change", "Biodiversity", "Agriculture", 
                                          "Industry and Commerce", "Mining", "Tourism", "Energy", "Transport", 
                                          "Disaster Risk Management and Human Settlements", "Waste Management", 
                                          "Health", "Gender; People Living With HIV and AIDS and other Vulnerable groups", 
                                          "Children and Youth", "Capacity Building", "Role of Meteorological Services", 
                                          "Technology Transfer", "Climate Change Education", "Public Awareness", 
                                          "Climate Change Governance"), amt = c(134, 3158, 91, 74, 2386, 
                                                                                528, 312, 252, 262, 1071, 519, 231, 52, 25, 32, 45, 23, 574, 
                                                                                15, 15, 88)), row.names = c(NA, 21L), class = "data.frame")
z$lab <- factor(z$no, labels = z$sector)
mycol <- colors()[444:500]
barplot(amt~lab, data = z, width = 4, space = 0.2, main = 'Zimbabwe budget by sector', xlab = 'Economic sectors', ylab = 'Amount in US $ millions', 
        col = mycol, cex.names = 0.6, horiz = F, las = 2)
legend('topright', legend=z$lab, fill = mycol, cex = 0.35, text.font = 3)

user_6574038 · Answer

barplot has builtin arguments for the legend, why not using them? Next, for the data using the height= argument is probably better, so the bars appear in the same order as in the table, use beside instead of horiz then; you can use names.arg= for the labels then, but they are actually superfluous because of the legend.

You definitely need more distinguishable colors, I use rainbow here.

Next, for the legend, just define legend.text=, and in args.legend= just put all the arguments you are used to from legend() in a list.

For better consistency I use the png device and not the one from Rstudio, which I think is more of a preview window.

Et voilá!

png('Rplot001.png', 800, 600)
barplot(z$am, beside=TRUE, col=rainbow(nrow(z), s=.6, v=.8),
        names.arg=z$sector,  ## just for demo, should be deleted
        legend.text=z$sector, args.legend=list(x='topright', cex=.9),
        width=4, space=0.2, main='Zimbabwe budget by sector', 
        xlab='Economic sectors', ylab='Amount in US $ millions', 
        cex.names=0.6, las=2)
dev.off()

Note: If you really want nice labels, check out my other answer.

Match legend text labels with their correct fill colors in barplot

2 Answers