A better scales::dollar() ?

I'm writing a quite large document in Rmarkdown which has financial data in it.  I format that data using scales::dollar() currently something like this:

require (scales)
x = 100000
cat (dollar (x, prefix ="?", big.mark=","))

?100,000

But actually, I'd quite like to get ?100k out in that instance so I'd do:

cat (dollar (x/10^3, prefix ="?", suffix="k" ))

?100k

But x could be 100 or 10,000,000.  I want some form of 'automatic' version that might give me something like:

require (scales)
y = 0:7
x = 1^y
dollar(x, prefix="?")

[1] "?1"          "?10"         "?100"        "?1,000"      "?10,000"     "?100,000"    "?1,000,000"  "?10,000,000"

But what I want is more like:

?1.00  ?10.00  ?100  ?1k  ?10k  ?100k  ?1m  ?10m

I'm sure I can write something as a little function, but before I do - is there something already out there?

I have a similar need to format milligrams through to kilograms.


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