How to increase size of legend in ggplot2

问题:

I'm new to the ggplot plotting library in R and can't work out how to increase the size of my legend. I know you can do axis manipulation with theme(axis...) but I can't find the correct argument to pass!

The code I use to produce the figure is here:

library(ggplot)
library(ggalluvial)

ggplot(data = wrong_cases_all,
       aes(axis1 = cae, axis2 = places,
           y = freq)) +
  scale_x_discrete(limits = c("CAE", "VGG16-Places365"))+
  xlab("Model") +
  geom_alluvium(aes(fill = freq)) +
  geom_stratum() + geom_text(stat = "stratum", label.strata = TRUE) +
  theme_minimal() 

Does anybody have any tips?

Example data:

wrong_cases_all <- read.table(header=TRUE, text = "cae places  freq
1    0      0 19462
2    0      1 23625
3    0      2 14431
4    0      3  9767
5    0      4 14025
6    1      0  8696
7    1      1 88510
8    1      2 12426
9    1      3 33408
10   1      4 16391
11   2      0   540
12   2      1  7908
13   2      2  2132
14   2      3  2429
15   2      4 11558
16   3      0  5215
17   3      1 19993
18   3      2  4361
19   3      3  5984
20   3      4  6993
21   4      0  2258
22   4      1  1382
23   4      2  1409
24   4      3   575
25   4      4  1338")

回答1:

Add

...
+ theme(
   legend.key.width = unit(1, "cm"),
   legend.key.height = unit(2, "cm")
  )

and change the units to what best fits your needs.