On 16/08/2013 20:47, Aleksey Vorona wrote:
On 8/16/13, Duncan Murdoch <murdoch.dun...@gmail.com> wrote:
On 13-08-15 6:07 PM, Aleksey Vorona wrote:
Dear R-team,
I've been using R for a while and decided to contribute some bug
fixes. The first bug I tried to solve was
https://bugs.r-project.org/bugzilla3/show_bug.cgi?id=15411
I have attached a patch with the fix to the bug and would love to hear
comments about its quality.
Also, while testing this bug I found another related issue:
format(complex(real=10, imaginary=4), digits = 1);
[1] "10+0i"
I think this should've been "10+4i". I have entered this as a bug
#15427. But a patch for formatComplex() would be a bigger change, than
the patch for formatReal() I made. So, before I start, I would like to
gauge your opinion.
Do you agree it is a bug?
No, it is a somewhat questionable design, but not a bug. You asked for
1 significant digit. format() will give both the real and imaginary
parts accurate to 1 significant digit. Since the real part has two
digits, it handles the imaginary part as 04, which is rendered as 0.
The questionable part of the design is that 11+4i would be rendered as
11+0i, i.e. two digits accuracy are given in the real part even though
you only asked for one. I think it would be better to be consistent
here. I think it makes more sense to give 11+4i (or 10+4i in your
example) than to give 10+0i for both, but I think that is a matter of
taste, rather than a bug fix.
I have also prepared a patch for the 15411 bug; I'll compare mine to
yours and commit something, but not for a week or so: I am mostly
offline until then.
Duncan Murdoch
Thank you for the reply. I sent this message to Duncan only.
Re-sending this again to the list. Sorry...
My interpretation of digits=1 was that I want both real and imaginary
parts to have 1 significant digits.
Consider this command, no digits parameter this time:
format(complex(real=5.6e+8, imaginary=2.1e+16));
[1] "0e+00+2.1e+16i"
I do not see a reason not to output the number as it was entered.
If it is not a bug, it should be documented. I'll check if I can help with that.
It is documented. You can help by reading the documentation for yourself!
digits: how many significant digits are to be used for numeric and
complex ‘x’. The default, ‘NULL’, uses
‘getOption("digits")’. This is a suggestion: enough decimal
places will be used so that the smallest (in magnitude)
number has this many significant digits, and also to satisfy
‘nsmall’. (For the interpretation for complex numbers see
‘signif’.)
^^^^^^
For ‘signif’ the recognized values of ‘digits’ are ‘1...22’, and
non-missing values are rounded to the nearest integer in that
range. Complex numbers are rounded to retain the specified number
of digits in the larger of the components.
-- Aleksey
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Brian D. Ripley, rip...@stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
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