[R] Formatting numbers for display

[arun]

Hi,

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"

#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"


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
P < (The "P Less Than" Company)
Phone: 1-866-PLessThan (1-866-753-7784)
Fax: 1-866-PLessThan (1-866-753-7784)
www.PLessThan.com

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