[R] Formatting numbers for display

[David Winsemius]

On Aug 2, 2012, at 8:27 PM, arun wrote:

> For your first condition, this could be used:
> gsub("(\\d)[.].*","\\1",498888888.85)
> [1] "498888888"
> Second condition:
> formatC(4333.78889,width=8,format="f",digits=2,flag="0")
> #[1] "04333.79"
>  formatC(884333.78889,width=8,format="f",digits=2,flag="0")
> #[1] "884333.79"
> Third condition:
> sprintf("%.3f",0.0123556)
> #[1] "0.012"

I didn't get the same results as requested with a wider variety of  
tests using those formatting methods. Here's what I could offer:

  form3 <- function (x) switch(findInterval(x, c( 0, 1, 10^7, Inf)),
                                      format(x, digits=3),
                                      formatC(x, width=8,  format="f",  
drop0trailing=FALSE),
                                      trunc(x) )

  tx <- c( 0.55555555, 55.555555555, 555555555555555.55555555)

 > sapply(tx, form3)
[1] "0.556"           " 55.5556"       "555555555555555"

(Still not getting the 8 digits in the intermediate value cases. Have  
not figured out how to get rid of leading space.)

-- 
David.
>
> #You can create a function similar to this. (This still have some  
> bugs).
>
>  fun1<-function(x)
>  ifelse(x>10^7,gsub("\\d)[.].*","\\1",x),ifelse(x<10^7 &  
> x>1,formatC(x,width=8,format="f",digits=2,flag="0"),sprintf("%.3f",x))
>  )
> fun1(488.85)
> #[1] "00488.85"
>  fun1(0.1233555)
> #[1] "0.123"
>

Using the vector of long 5's

 > sapply(tx, fun1)
[1] "0.556"           "00055.56"        "555555555555556"

>
> fun1(VALUES)
> # [1] "123456789"  "12345678"   "1234567.90" "123456.89"  "12345.79"
>  #[6] "01234.68"   "00123.57"   "00012.46"   "00001.35"   "0.123"
> #[11] "0.012"      "0.001"
>
>
> A.K.
>
>
>
> ----- Original Message -----
> From: Dennis Fisher <fisher at plessthan.com>
> To: r-help at stat.math.ethz.ch
> Cc:
> Sent: Thursday, August 2, 2012 10:34 PM
> Subject: [R] Formatting numbers for display
>
> Colleagues
>
> R 2.15.1
> OS X
>
> I have a lengthy script that generates a positive number that I  
> display in a graphic using text.  The range of possible values is  
> quite large and I am looking for an efficient means to format.
>     1.  If the number is large (e.g., > 10^7), I want to display  
> only the integer portion.
>     2.  If it is less than 10^7 but > 1, I want to display 8  
> characters, e.g.,
>         12345.78
>         1234.678
>         123.5678
>     3.  If it is less than 1, I want to display at least three  
> significant digits, e.g.
>         0.123
>         0.0123
>         0.00123
>         0.000123
> If there are any inconsistencies in my proposal, I apologize.
>
> I can accomplish this by brute force with conditionals, - 
> ceiling(log10(VALUE)), round.  However, I expect that there is a  
> more efficient approach, possibly using sprint.
>
> For the "dput"-ers, use the following as potential input:
> VALUES    <- c(123456789, 12345678, 1234567.9, 123456.89, 12345.789,  
> 1234.6789, 123.56789, 12.456789, 1.3456789, 0.123456789,  
> 0.0123456789, 0.00123456789)
>
> Thanks for any thoughts.
>
> Dennis
>
> Dennis Fisher MD


David Winsemius, MD
Heritage Laboratories
West Hartford, CT