[R] numeric format

[Don MacQueen]

While we're at it, and since you're new...

Your example will be much easier for r-help folks to read if you do 
it like this:

j <- 0.4
for(i in 1:20) {
   j=j+0.1
   cp[i] <- pnorm(-j*3)*10^6
   ratio[i] <- j
}

  table <- data.frame(ratio,cp)
  table

But the loop is unnecessary. Try

j <- seq(0.5, by=0.1, length=20)
tbl <- data.frame(ratio=j, cp= pnorm(-3*j)*10^6)


Also, the formatting you are getting is not, I don't think, the default. I get:

>  j <- seq(0.5, by=0.1, length=20)
>  tbl <- data.frame(ratio=j, cp= pnorm(-3*j)*10^6)
>  head(tbl)
   ratio        cp
1   0.5 66807.201
2   0.6 35930.319
3   0.7 17864.421
4   0.8  8197.536
5   0.9  3466.974
6   1.0  1349.898

Note that they are aligned to all have 3 places after the decimal point.

Do you want the actual cp values to be adjusted to have some other 
number of decimal places, or do you just want the format changed?

For the former, use, for example, round(cp,1).

For the latter, it kind of depends on your ultimate goal. If you want 
to control the number of decimal places, because you're going to move 
it into a report, for example, you might try looking into the 
formatC() and use something like

formatC(tbl$cp,digits=1,format='f')

As in,

>  tbl$cp <- formatC(tbl$cp,digits=1,format='f')
>  head(tbl)
   ratio      cp
1   0.5 66807.2
2   0.6 35930.3
3   0.7 17864.4
4   0.8  8197.5
5   0.9  3467.0
6   1.0  1349.9

To get rid of the row labels, you will have to use Rolf's suggestion, 
or perhaps delve into the write.table function.

-Don


At 3:41 PM -0800 2/26/08, cvandy wrote:
>Thanks, Erik,
>This is a partial copy of my code.  I want to get rid of the left column of
>integers and I want to control the number of decimal places after the
>decimal point.
>
>  > j<-0.4
>>   for(i in 1:20){
>+ j=j+0.1;cp[i]<-pnorm(-j*3)*10^6;ratio[i]<-j}
>  >  table<-data.frame(ratio,cp)
>>  table
>    ratio                   cp
>1    0.5      66807.201268858
>2    0.6     35930.3191129258
>3    0.7     17864.4205628166
>4    0.8     8197.53592459613
>5    0.9     3466.97380304067
>6
>
>>  CHV
>
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>
>
>
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>
>______________________________________________
>R-help at r-project.org mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.


-- 
---------------------------------
Don MacQueen
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062
macq at llnl.gov