Formatting Decimal places in R

Question

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)

Answer 1

You can try my package formattable.

> # devtools::install_github("renkun-ken/formattable")
> library(formattable)
> x <- formattable(1.128347132904321674821, digits = 2, format = "f")
> x
[1] 1.13

The good thing is, x is still a numeric vector and you can do more calculations with the same formatting.

> x + 1
[1] 2.13

Even better, the digits are not lost, you can reformat with more digits any time :)

> formattable(x, digits = 6, format = "f")
[1] 1.128347

Answer 2

The function formatC() can be used to format a number to two decimal places. Two decimal places are given by this function even when the resulting values include trailing zeros.

Answer 3

You can format a number, say x, up to decimal places as you wish. Here x is a number with many decimal places. Suppose we wish to show up to 8 decimal places of this number:

x = 1111111234.6547389758965789345
y = formatC(x, digits = 8, format = "f")
# [1] "1111111234.65473890"

Here format="f" gives floating numbers in the usual decimal places say, xxx.xxx, and digits specifies the number of digits. By contrast, if you wanted to get an integer to display you would use format="d" (much like sprintf).

Answer 4

Note that numeric objects in R are stored with double precision, which gives you (roughly) 16 decimal digits of precision - the rest will be noise. I grant that the number shown above is probably just for an example, but it is 22 digits long.

Answer 5

I'm using this variant for force print K decimal places:

# format numeric value to K decimal places
formatDecimal <- function(x, k) format(round(x, k), trim=T, nsmall=k)

Answer 6

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.