Formatting Decimal places in R

user_170352 0
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I have a number, for example 1.128347132904321674821 that I would like to show as only two decimal places when output to screen (or written to a file). How does one do that? 

x <- 1.128347132904321674821

EDIT:

The use of: 

options(digits=2)

Has been suggested as a possible answer. Is there a way to specify this within a script for one-time use? When I add it to my script it doesn't seem to do anything different and I'm not interested in a lot of re-typing to format each number (I'm automating a very large report).

--

Answer: round(x, digits=2)

r-faq r rounding formatting
15 Answers

for 2 decimal places assuming that you want to keep trailing zeros

sprintf(5.5, fmt = '%#.2f')

which gives

[1] "5.50"

As @mpag mentions below, it seems R can sometimes give unexpected values with this and the round method e.g. sprintf(5.5550, fmt='%#.2f') gives 5.55, not 5.56

user_5384030

if you just want to round a number or a list, simply use 

round(data, 2)

Then, data will be round to 2 decimal place.

user_94736430

I wrote this function that could be improve but looks like works well in corner cases. For example, in the case of 0.9995 the vote correct answer gives us 1.00 which is incorrect. I use that solution in the case that the number has no decimals.

round_correct <- function(x, digits, chars = TRUE) {
  if(grepl(x = x, pattern = "\\.")) {
    y <- as.character(x)
    pos <- grep(unlist(strsplit(x = y, split = "")), pattern = "\\.", value = FALSE)
    if(chars) {
      return(substr(x = x, start = 1, stop = pos + digits))
    }
    return(
      as.numeric(substr(x = x, start = 1, stop = pos + digits))
    )
  } else {
    return(
      format(round(x, 2), nsmall = 2)
    )
  }
}

Example:

round_correct(10.59648, digits = 2)
[1] "10.59"
round_correct(0.9995, digits = 2)
[1] "0.99"
round_correct(10, digits = 2)
[1] "10.00"
user_107236940

here's my approach from units to millions. digits parameter let me adjust the minimum number of significant values (integer + decimals). You could adjust decimal rounding inside first.

number <-function(number){
  result <- if_else(
    abs(number) < 1000000,
    format(
      number, digits = 3,
      big.mark = ".",
      decimal.mark = ","
    ),
    paste0(
      format(
        number/1000000,
        digits = 3,
        drop0trailing = TRUE,
        big.mark = ".",
        decimal.mark = ","
      ),
      "MM"
    )
  )
  # result <- paste0("$", result)
  return(result)
}
user_23197470 
library(dplyr)
# round the numbers
df <- df %>%
  mutate(across(where(is.numeric), .fns = function(x) {format(round(x, 2), nsmall = 2)}))

Here I am changing all numeric values to have only 2 decimal places. If you need to change it to more decimal places

# round the numbers for k decimal places
df <- df %>%
  mutate(across(where(is.numeric), .fns = function(x) {format(round(x, k), nsmall = k)}))

Replace the k with the desired number of decimal places

user_144480380
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