ggplot color legend shape mixes alphanumeric and shape

Question

The inclusion of ggrepel in a ggplot leads to a funny shape in the legend:

.

Q: How do I replace this with a normal shape?

Sample code:

data(mtcars)
library(ggplot2)
library(ggrepel)

ggplot(mtcars, aes(x = mpg, y = wt, color = factor(vs), size = factor(cyl))) +
  geom_point() +
  geom_text_repel(aes(label = rownames(mtcars)), size = 5)

sessionInfo:

R version 3.2.3 (2015-12-10)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 16.04.1 LTS

locale:
  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=nl_NL.UTF-8        LC_COLLATE=en_US.UTF-8     LC_MONETARY=nl_NL.UTF-8    LC_MESSAGES=en_US.UTF-8    LC_PAPER=nl_NL.UTF-8      
[8] LC_NAME=C                  LC_ADDRESS=C               LC_TELEPHONE=C             LC_MEASUREMENT=nl_NL.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
  [1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
  [1] magrittr_1.5       ggrepel_0.5        ggplot2_2.1.0.9000

loaded via a namespace (and not attached):
  [1] labeling_0.3     colorspace_1.2-6 scales_0.4.0     assertthat_0.1   plyr_1.8.4       rsconnect_0.4.3  tools_3.2.3      gtable_0.2.0     tibble_1.1       Rcpp_0.12.6      grid_3.2.3       digest_0.6.10   
[13] munsell_0.4.3  

Answer 1

ggrepel has show.legend argument, so we need show.legend = FALSE as below:

show.legend
logical. Should this layer be included in the legends? NA, the default, includes if any aesthetics are mapped. FALSE never includes, and TRUE always includes.

ggplot(mtcars, aes(x = mpg, y = wt, color = factor(vs), size = factor(cyl))) +
  geom_point() +
  geom_text_repel(aes(label = rownames(mtcars)), size = 5, show.legend = FALSE)

As a side note, prepare the data outside ggplot for clarity:

#fix the data
plotDat <- mtcars
plotDat$vs <- as.factor(plotDat$vs)
plotDat$cyl <- as.numeric(as.factor(plotDat$cyl))
plotDat$myLabel <- rownames(plotDat)

#then plot
ggplot(plotDat, aes(x = mpg, y = wt,
                    color = vs, size = cyl,
                    label = myLabel)) +
  geom_point() +
  geom_text_repel(size = 5, show.legend = FALSE)