使用r和ggplot如何指定特定的十六进制颜色/颜色值来表示不同的字符值

Question

Assuming is.character(MyColours) = TRUE where MyColours contains a number of hexadecimal colour values.

How do I ensure that when I want to plot using ggplot I can ensure that MyColours[1] will always be used to represent "Ford" and MyColour[3] will represent "Toyota" when I can't guarantee the order "Ford" or "Toyota" will appear in the observations I use to plot.

While the geo_bar example below was helpful and did remind me to add column names to MyColours I'm hoping to plot lines not bars

    ggplot(MyData, aes(x = TimePeriod, y = CountOfItems, 
group = Account, color = scale_fill_manual(values = MyColours))) 
    + geom_line(size = 1) 
    + theme(axis.text.x = element_text(angle = 90, vjust = 0.5, hjust=1))

I get the error Aesthetics must either be length one, or the same length as the dataProblems:scale_fill_manual(values = MyColours) even when length(MyColours) is equal to length(unique(MyData$Account))

Sample Data

dput(MyData)
structure(list(Account = structure(c(1L, 2L, 1L, 2L), .Label = c("Mazda RX4", 
"Toyota Corolla"), class = "factor"), CountOfItems = c(14, 120, 
23, 345), TimePeriod = structure(c(1L, 2L, 2L, 3L), .Label = c("2010-12", 
"2011-01", "2011-02"), class = "factor")), .Names = c("Account", 
"CountOfItems", "TimePeriod"), row.names = c(NA, -4L), class = "data.frame")

Is it possible to use scale_fill_manual with line plots?

Answer 1

You could name MyColours , eg like this:

MyColour <- c("#FF0000", "#00FF00", "#0000FF") 
names(MyColour) <- c("Mazda RX4", "Toyota Corolla", "Fiat 128")

df <- mtcars[c("Mazda RX4", "Toyota Corolla", "Fiat 128"), ]
df$car <- rownames(df)
library(ggplot2)
ggplot(df, aes(x = car, y = mpg, fill = car)) +
  geom_bar(stat = "identity") + 
  scale_fill_manual(values = MyColour)