CODEWITHSUNDEEP
rplotggplot2
Crops
Crops

Reputation: 5154

ggplot2 of categorical data - grayscale/BW theme for enhanced readability

I am trying to plot a line graph by group in R using ggplot2 as follows. It is intended for a grayscale print.

library(ggplot2)

# Summarise data
mry <- do.call(rbind, by(movies, round(movies$rating), function(df) {
  nums <- tapply(df$length, df$year, length)
  data.frame(rating=round(df$rating[1]), year = as.numeric(names(nums)), number=as.vector(nums))
}))

p <- ggplot(mry, aes(x=year, y=number, colour=factor(rating)))
p + geom_line() + scale_color_grey() + theme_bw()

enter image description here

However the clarity is lacking in the resulting plot as there are 10 groups involved. How to adjust the colors/pch/line style in ggplot2 for better readability in such a case where large number of groups are involved?

Upvotes: 0

Views: 1211

Answers (2)

jlhoward
jlhoward

Reputation: 59415

I'd be inclined to use facets, like this:

ggplot(mry, aes(x=year, y=number))+
  geom_line() + 
  scale_color_grey() + 
  theme_bw() + 
  facet_grid(rating~.)

Obviously this would be better in portrait mode, but even at this minuscule scale you can tell that ratings of 1,2,3,9, and 10 are extremely rare, and that the most common ratings are 6 and 7 (at least recently). This is much more than you can get from plotting everything on top of each other.

Upvotes: 2

mpalanco
mpalanco

Reputation: 13580

An option to improve readability is to use linetype instead of colour. But still, 10 groups are probably too many. You could try to add different point shapes with geom_point

p <- ggplot(mry, aes(x=year, y=number, linetype =factor(rating)))
p + geom_line() + scale_color_grey() + theme_bw()

Upvotes: 1

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