Format number in R with both comma thousands separator and specified decimals

Question

I\'d like to format numbers with both thousands separator and specifying the number of decimals. I know how to do these separately, but not together.

For example, I

Answer 1

format not formatC:

format(round(as.numeric(1000.64), 1), nsmall=1, big.mark=",") # 1,000.6