Question

I’m working on a data visualization project and am making some line graphs. This is my data set:

groupA <- read.csv("afcongroupA.csv", header=T, row.names=NULL)
groupA
    Date               Team Position
1   1/12       South Africa       56
2   1/12             Angola       85
3   1/12            Morocco       61
4   1/12 Cape Verde Islands       58
5   4/12       South Africa       71
6   4/12             Angola       78
7   4/12            Morocco       62
8   4/12 Cape Verde Islands       76
9   8/12       South Africa       67
10  8/12             Angola       85
11  8/12            Morocco       68
12  8/12 Cape Verde Islands       78
13 12/12       South Africa       87
14 12/12             Angola       84
15 12/12            Morocco       72
16 12/12 Cape Verde Islands       69

I then plotted them on a line graph to show the rise of decline in position standings:

groupA$Date <- factor(groupA$Date, levels=groupA$Date[!duplicated(groupA$Date)])
ggplot(groupA, aes(x=Date, y=Position, colour=Team, group=Team)) + geom_line()

What I want to do is reverse the y-axis so that the largest number is at the bottom. I tried this bit of code:

groupA <- coord_flip() + scale_x_reverse()

But I get this error message:

Error in coord_flip() + scale_x_reverse() : 

non-numeric argument to binary operator

I’m using R 2.15.2 on a Mac running OS X.

Answer 1

As your column Date is a factor then scale_x_reverse() won’t work. One solution is to order your levels of factors in data frame

groupA$Date <- factor(groupA$Date, levels=rev(unique(groupA$Date)))

Then just use your code to make plot and flip axis.

ggplot(groupA, aes(x=Date, y=Position, colour=Team, group=Team)) +
      geom_line()+coord_flip()