Represent numeric value with typical dollar amount format

Question

I have a data frame storing the dollar amount, it looks like this

> a
  cost
1 1e+05
2 2e+05

I would like it can be shown as this

> a  
  cost
1 $100,000
2 $200,000

How to do that in R?

Answer 1

DF <- data.frame(cost=c(1e4, 2e5))

#assign a class    
oldClass(DF$cost) <- c("money", oldClass(DF$cost))

#S3 print method for the class    
print.money <- function(x, ...) {
  print.default(paste0("$", formatC(as.numeric(x), format="f", digits=2, big.mark=",")))
}

#format method, which is necessary for formating in a data.frame   
format.money  <- function(x, ...) {
  paste0("$", formatC(as.numeric(x), format="f", digits=2, big.mark=","))
}

DF
#         cost
#1  $10,000.00
#2 $200,000.00

Answer 2

This will get you everything except the commas:

> sprintf("$%.2f", seq(100,100000,by=10000)/7)
 [1] "$14.29"    "$1442.86"  "$2871.43"  "$4300.00"  "$5728.57"  "$7157.14"  "$8585.71"  "$10014.29" "$11442.86" "$12871.43"

Getting those is pretty complicated, as shown in these questions:

• How can I format currency with commas in C?
• How to format a number from 1123456789 to 1,123,456,789 in C?

Luckily, this is implemented in the scales package:

library('scales')
> dollar_format()(c(100, 0.23, 1.456565, 2e3))
## [1] "$100.00"   "$0.23"     "$1.46"     "$2,000.00"
> dollar_format()(c(1:10 * 10))
## [1] "$10"  "$20"  "$30"  "$40"  "$50"  "$60"  "$70"  "$80"  "$90"  "$100"
> dollar(c(100, 0.23, 1.456565, 2e3))
## [1] "$100.00"   "$0.23"     "$1.46"     "$2,000.00"
> dollar(c(1:10 * 10))
## [1] "$10"  "$20"  "$30"  "$40"  "$50"  "$60"  "$70"  "$80"  "$90"  "$100"
> dollar(10^(1:8))
## [1] "$10"          "$100"         "$1,000"       "$10,000"      "$100,000"     "$1,000,000"   "$10,000,000"  "$100,000,000"

Answer 3

You can use the currency() function from the formattable package. With OP's example

a <- data.frame(cost = c(1e+05, 2e+05))
a

   cost
1 1e+05
2 2e+05

library(formattable)
a$cost <- currency(a$cost, digits = 0L)
a

      cost
1 $100,000
2 $200,000

By default, 2 digits after the decimal point are shown. This has been overruled using the digits parameter to meet OP's expectations.

The benfit of formattable is that numbers are still numbers even with a format attached, e.g.,

a$cost2 <- 2 * a$cost
a

      cost    cost2
1 $100,000 $200,000
2 $200,000 $400,000

Answer 4

A very simple way is

library(priceR)
values <- c(1e5, 2e5)
format_dollars(values)

# [1] "$100,000" "$200,000"

Notes

• Add decimal places with format_dollars(values, 2) i.e. "$100,000.00" "$200,000.00"
• For other currencies use format_currency(values, "€") which gives "€100,000" "€200,000" etc