ggplot2: Order in legend alphabetically instead of following the order of appearance in the dataset

Question

I am producing a ggplot2 line plot from `AESRD 2013 - SCO Bitumen - 7y.csv` in this folder. The file is automatically created on a website according to my wishes. These are several time series showing some production values, each named according to the column "Compilation". So I grouped according to "Compilation". See this excerpt of my code in the file `plotter.r` available in the same folder (see above). ``` # "dt" is the dataframe derived from the csv file. # "thinned" is some vector of x-values that tells where to draw the special symbols. p = ggplot(dt, aes(Date, Value, colour= Compilation, group = Compilation, size = plotParameter), guide=FALSE) p = p + geom_point(data=dt[thinned,],aes(as.Date(Date), Value, colour= Compilation, shape = Compilation), size = 5) p = p + scale_shape_manual(values = seq(0,20)) p = p + geom_line(guide = FALSE) p = p + scale_colour_manual(values=cbPalette) #cbPalette is already defined p = p + scale_size(range=c(0.5, 2), guide=FALSE) p = p + scale_y_co…

Accepted Answer

apply `breaks` in both scales(`scale_color_manual` and `scale_shape_manual`) . If we did just one, they wouldn't match, and ggplot would split them into two legends, rather than merging them

One such example is:

```
> library(ggplot2)
> ggplot(mtcars, aes(wt, mpg, shape=factor(cyl))) + geom_point() + theme_bw()
> library(ggplot2)
> bp <- ggplot(data=PlantGrowth, aes(x=group, y=weight, fill=group)) + geom_boxplot()
> bp
```

```
bp + scale_fill_discrete(breaks=c("trt1","ctrl","trt2"))
```

To reverse

```
bp + scale_fill_discrete(breaks = rev(levels(PlantGrowth$group)))
```

also try

```
bp + scale_fill_discrete(breaks = unique(levels(PlantGrowth$group)))
```

ggplot2: Order in legend alphabetically instead of following the order of appearance in the dataset

Solution

Problem