How to read in Unicode code points into R data frame - r

Question

I have a two-column text file of Unicode code points of interest (Greek symbols in this test, but any set of Unicode characters, generically):
$ cat ut.txt
\u0391 Α
\u0392 Β
\u0393 Γ
\u0394 Δ
\u0395 Ε
\u0396 Ζ
...
I'd like to read this into R, so that I can kick the tires on the typeface I am using to make plots that contain mathematical or other Unicode symbols.
As a minimally-reproducible start, I start by drawing a random sample from this Unicode table:
set.seed(42)
df <- data.frame(date = 1:10 , value = cumsum(runif(10 , max = 10)) )
ut <- read.table("ut.txt", allowEscapes=TRUE)
df$labels <- paste("\\", sample(ut$V1, size=10), sep="")
The head of the data frame looks like this:
date value labels
1 1 9.14806 \\u03A8
2 2 18.51881 \\u03BB
3 3 21.38021 \\u03C4
4 4 29.68469 \\u039C
5 5 36.10214 \\u03A6
6 6 41.29310 \\u03C2
When I plot from the labels column, R writes out the literal string, and not the Unicode character it represents:
library(ggplot2)
p <- ggplot(df, aes(x=date, y=value, label=labels))
p <- p + geom_line()
p <- p + ggtitle("5\u03BCg (\u03C7-squared test)") # control title
p <- p + geom_text()
library(Cairo)
ggsave("test.pdf", device=cairo_pdf)
Here is what the test plot looks like:
What I would like to see are Greek symbols at each point along the line, instead of their literal string equivalents.
How can I read a set of Unicode code points from a text file and use them directly?
Important note: I did test sampling from the second column of ut.txt, which works. However, I am specifically interested in learning what is required to correctly read in the encoded code point equivalent from a file.

Answer 1

Here's one approach using scale_shape_manual. I included the code of how I entered your data so I didn't have to read the text file
set.seed(42)
df <- data.frame(date = 1:10 , value = cumsum(runif(10 , max = 10)) )
df <- df[1:6, ]
## Following line stands in for what you read from `read.table`. In your solution, just use what you got from `read.table`
df$labels <- c("\u03A8", "\u03BB", "\u03C4", "\u039C", "\u03A6", "\u03C2")
library(ggplot2)
p <- ggplot(df, aes(x=date, y=value, shape = labels))
p <- p + geom_line()
p <- p + ggtitle("5\u03BCg (\u03C7-squared test)") # control title
p <- p + geom_point(size = 5) + scale_shape_manual(values = df$labels)
p

Answer 2

It also works with geom_text() (Infinite thanks to #astrofunkswag for its smart way to teach us how to include symbols properly):
library(ggplot2)
#Code
ggplot(df, aes(x=date, y=value))+
geom_line()+
ggtitle("5\u03BCg (\u03C7-squared test)")+
geom_text(label=c("\u03A8", "\u03BB", "\u03C4", "\u039C", "\u03A6", "\u03C2"))
Output: