绘图颜色R不正确

Question

I am using the following code to generate a plot:

library(plotrix)

dat_fn = "emptiness.csv"
storage_fn = "final/results/emptiness_values.png"
data <- read.csv(dat_fn, header = TRUE, sep = "\t")

png(storage_fn)
sizeplot(data$PercentEmpty, data$PercentUniform, col = data$QuestionType)
legend("topleft", legend = levels(data$QuestionType), pch = "o", col = 
unique(data$QuestionType))
dev.off()

I should be getting two black points in the bottom left, and one red in the top right. Instead, I am getting one black and one red in the bottom left, and one black in the top right. (See graph below.) I am completely stumped - what could be going on here? I double checked my data three times, the data is not the problem.

Plot

My data is:

ColumnName  PercentEmpty    PercentUniform  QuestionType
D   0.0 5.155436407691911e-05   a
E   0.0 0.00030932618446151465  a
F   0.14146517502706604 0.09666443264422334 b

Thanks!

Answer 1

I think the processing sizeplot does ends up reordering some points. You don't seem to be using sizeplot 's feature of automatically resizing points, so I'd recommend just using plot instead which works just fine.

If you do need sizeplot, here's a hacky work-around:

with(data, plot(PercentEmpty, PercentUniform, type = "n"))
with(subset(data, QuestionType == "a"), sizeplot(PercentEmpty, PercentUniform, col = 1, add = TRUE))
with(subset(data, QuestionType == "b"), sizeplot(PercentEmpty, PercentUniform, col = 2, add = TRUE))