无法将一些unicode字符写入文件

Question

Let's consider the following code:

> cat('\u2077\u2078\u2079 \u2087\u2088\u2089')
⁷⁸⁹ ₇₈₉
> out <- file("out.txt", "w", encoding = 'utf-8')
> cat('\u2077\u2078\u2079 \u2087\u2088\u2089', file=out)
> close(out)

the content of out.txt is:

78<U+2079> 789

The sub/superscript form is lost and for exponent 9 it's the codepoint that is printed.

What's happening here? How can I have the correct form of the characters in the file as they are printed in the RStudio console?

Versions: RStudio 1.1.436 / R 3.5.2 / Windows 10

Answer 1

Aargh, windows and UTF-8!

I've been puzzling as well, and this works for me

options(encoding='native.enc')
out <- file('out.txt', open='w', encoding = 'UTF-8')
writeLines('\u2077\u2078\u2079 \u2087\u2088\u2089', 'out.txt', useBytes = TRUE)
close(out)
readback <- readLines('out.txt', encoding='UTF-8')

My setup is a bit older (my most used setup is OSX): Rstudio 0.99.903/R 3.3.1/Windows 7

The very strangest thing I've encountered is that it stops working if you set options(encoding='UTF-8')

And finally, I noticed all mentions of UTF-8 are in uppercase, I see you used lowercase, I'm not sure if that makes a difference.