[R] mysterious rounding digits output

[Ted Harding]

Well pointed out, Jim!
It is infortunate that the documentation for options(digits=...)
does not mention that these are *significant digits* and not
*decimal places* (which is what Joshua seems to want):
  "‘digits’: controls the number of digits to print when
  printing numeric values."

On the face of it, printing the value "0,517" of 'ccc' looks
like printing 4 digits! Joshua's could look even worse if 'ddd'
had values in the 1000s!

To achieve exactly what Joshua seems to want, use the round()
function. Starting with his original assignment of values to
the variable itemInfo, the result of round(itemInfo,digits=3) is:

            aaa   bbb   ccc   ddd    eee
skill     1.396 6.225 0.517 5.775  2.497
predict   1.326 5.230 0.462 5.116 -2.673
waiting   1.117 4.948    NA    NA     NA
complex   1.237 4.170 0.220 4.713  5.642
novelty   1.054 4.005 0.442 4.260  2.076
creative  1.031 3.561 0.362 3.689  2.549
evaluated 0.963 3.013    NA    NA     NA
body      0.748 2.238 0.596 2.019  0.466
control   0.620 2.149    NA    NA     NA
stakes    0.541 1.905 0.227 2.020  2.343
spont     0.496 1.620    NA    NA     NA
chatter   0.460 1.563 0.361 1.382  0.540
present   0.428 1.236 0.215 1.804  2.194
reward    0.402 1.101 0.288 1.208  0.890
feedback  0.283 0.662    NA    NA     NA
goal      0.237 0.474    NA    NA     NA

Best wishes to all,
Ted.


On Thu, 2018-05-31 at 15:30 +1000, Jim Lemon wrote:
> Hi Joshua,
> Because there are no values in column ddd less than 1.
> 
> itemInfo[3,"ddd"]<-0.3645372
> itemInfo
>             aaa   bbb   ccc   ddd    eee
> skill     1.396 6.225 0.517 5.775  2.497
> predict   1.326 5.230 0.462 5.116 -2.673
> waiting   1.117 4.948    NA 0.365     NA
> complex   1.237 4.170 0.220 4.713  5.642
> novelty   1.054 4.005 0.442 4.260  2.076
> creative  1.031 3.561 0.362 3.689  2.549
> evaluated 0.963 3.013    NA    NA     NA
> body      0.748 2.238 0.596 2.019  0.466
> control   0.620 2.149    NA    NA     NA
> stakes    0.541 1.905 0.227 2.020  2.343
> spont     0.496 1.620    NA    NA     NA
> chatter   0.460 1.563 0.361 1.382  0.540
> present   0.428 1.236 0.215 1.804  2.194
> reward    0.402 1.101 0.288 1.208  0.890
> feedback  0.283 0.662    NA    NA     NA
> goal      0.237 0.474    NA    NA     NA
> 
> digits specifies the number of significant digits ("It is a suggestion
> only"), so when at least one number is padded with a leading zero it
> affects the formatting of the other numbers in that column. I suspect
> that this is an esthetic consideration to line up the decimal points.
> 
> Jim
> 
> 
> On Thu, May 31, 2018 at 11:18 AM, Joshua N Pritikin <jpritikin using pobox.com> wrote:
> > R version 3.5.0 (2018-04-23) -- "Joy in Playing"
> > Platform: x86_64-pc-linux-gnu (64-bit)
> >
> > options(digits=3)
> >
> > itemInfo <- structure(list("aaa" = c(1.39633732316667, 1.32598263816667,  1.11658324066667, 1.23651072616667, 1.05368679983333, 1.03100737383333,  0.9630728395, 0.7483865045, 0.620086646166667, 0.5411017985,  0.496397607833333, 0.459528044666667, 0.427877047833333, 0.402085979666667,  0.283161181233333, 0.236896277233333), "bbb" = c(6.22533860696667,  5.229736804, 4.94816041772833, 4.17020503255333, 4.00453781427167,  3.56058007398333, 3.0125202404, 2.23782358733333, 2.14863910661167,  1.90460903044777, 1.62001089796667, 1.56341257968151, 1.23618558850667,  1.10086688908262, 0.661981500639833, 0.47397754310745), "ccc" = c(0.5165911355,  0.462204707666667, NA, 0.219635924333333, 0.441863780833333,  0.361502865833333, NA, 0.596137946666667, NA, 0.226984771566667,  NA, 0.360922661583333, 0.2145347068, 0.287756249483333, NA, NA ), "ddd" = c(5.77538400186667,  5.115877113, NA, 4.71294520316667, 4.25952652129833, 3.68879921863167,  NA, 2.01942456211145, NA, 2.02032557108, NA, 1.381810875
>  9571,  1.80436759778167, 1.20789851993367, NA, NA), "eee" = c(2.49725347166667,  -2.67340172316667, NA, 5.64195206333333, 2.07633555233333, 2.548949539,  NA, 0.465537272243167, NA, 2.34255027516667, NA, 0.5400824922975,  2.1935000655, 0.890007976866667, NA, NA)), row.names = c("skill",  "predict", "waiting", "complex", "novelty", "creative", "evaluated",  "body", "control", "stakes", "spont", "chatter", "present", "reward",  "feedback", "goal"), class = "data.frame")
> >
> > itemInfo  # examine column ddd
> >
> > When I try this, column ddd has 1 fewer digits than expected. See the
> > attached screenshot.
> >
> > Why don't all the columns have the same number of digits displayed?
> >
> > --
> > Joshua N. Pritikin, Ph.D.
> > Virginia Institute for Psychiatric and Behavioral Genetics
> > Virginia Commonwealth University
> > PO Box 980126
> > 800 E Leigh St, Biotech One, Suite 1-133
> > Richmond, VA 23219
> > http://exuberant-island.surge.sh
> >
> > ______________________________________________
> > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > 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.
> >
> 
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.