[R] Bug/Error in formatC? (Was: Why doesn't formatC( x, digits=2, format= "g")...)
Peter Dunn
dunn at usq.edu.au
Tue Jun 10 01:25:07 CEST 2008
Hi all
After posting what follows, Duncan Murdoch suggested perhaps a bug
in formatC, or an error on documentation. Any comments?
In particular, bug, error or not, any ideas about how I can
consistently get two significant figures to print?
P.
---------- Original Message ----------
Hi all
I am not a C programmer, but I am trying to understand formatC to
get consistent printing of reals to a given number of significant
digits.
Can someone please explain this to me? These first three give what
I expect on reading ?formatC:
> formatC(0.0059999, digits=2,format="fg",flag="#")
[1] "0.0060"
> formatC(0.59999, digits=2,format="fg",flag="#")
[1] "0.60"
> formatC(5.9999, digits=2,format="fg",flag="#")
[1] "6.0"
This seems consistent with what I read (but perhaps do not
understand) in ?formatC, where I read this:
digits the desired number of digits after the decimal
point (format = "f") or significant digits (format = "g",
= "e" or = "fg").
Since I am using format="fg" and digits=2, so I am expecting two
significant digits to always show, which I have above. So I fail to
understand this:
> formatC(0.000059999, digits=2,format="fg",flag="#")
[1] "0.00006"
> formatC(0.000059, digits=2, format="fg",flag="#")
[1] "0.000059"
I was expecting both of these to produce "0.000059". But in the
first case above, I get one significant digit only.
I'm obviously misunderstanding something; can someone enlighten me?
(No doubt, someone will point out a nuance of the help files I
didn't understand!)
Also, since the above obviously doesn't do what I hoped
(consistently printing two sig figs), could someone also explain
how I can consistently get two significant figures in situation
like above?
Thanks as always.
P.
--
Dr Peter Dunn | dunn <at> usq.edu.au
Faculty of Sciences, USQ; http://www.sci.usq.edu.au/staff/dunn
Aust. Centre for Sustainable Catchments: www.usq.edu.au/acsc
This email (including any attached files) is confidentia...{{dropped:15}}
More information about the R-help
mailing list