I am not sure that format solves the problem (although again I may
well be missing something)
# trailing zeros on large numbers
>format(vec, digits=4, scientific=F)
[1] " 0.8000" " 123.4567" " 0.1235" " 7.6543"
"7654321.0000"
# misses trailing zeros
> format(vec[1], digits=4, scientific=F)
[1] "0.8"
I guess I could resort to writing a routine that called format with
different arguments depending on the magnitude of each number in the
vector, but I was hoping for a cleaner solution. Any thoughts?
On 14 Aug 2008, at 14:57, Prof Brian Ripley wrote:
I think you missed the function called 'format'. R's internal print
routines (used by format) calculate the format passed to (C level)
sprintf based on the input, including 'digits'. Just make sure you
pass one number at a time to format() if you don't want a common
layout for all the numbers.
On Thu, 14 Aug 2008, [EMAIL PROTECTED] wrote:
Hi everyone,
I can't figure out how to format numbers to have a certain number
of significant figures (as opposed to decimal places) without using
scientific notation and including trailing zeros if necessary.
e.g. I would like to achieve the following:
0.800001 ---> 0.8000
123.4567 ---> 123.4
0.1234567 ---> 0.1234
7.654321 ---> 7.654
7654321 ---> 7654000
It seems like it should be simple, but I can't seem to do this
using sprintf. Specifically, I get the following outputs:
vec = c(0.800001, 123.4567, 0.1234567, 7.654321, 7654321)
# this specifies precision after decimal point, rather than
significant figures
sprintf("%.4f", vec)
[1] "0.8000" "123.4567" "0.1235" "7.6543"
"7654321.0000"
# uses scientific notation, but significant figures are correct
sprintf("%.3e", vec)
[1] "8.000e-01" "1.235e+02" "1.235e-01" "7.654e+00" "7.654e+06"
# correct number of significant figures, and without scientific
notation, but has trailing zeros on large numbers
sprintf("%.4f", sprintf("%.3e", vec))
[1] "0.8000" "123.5000" "0.1235" "7.6540"
"7654000.0000"
Am I missing something obvious and can someone help me?
Many thanks
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--
Brian D. Ripley, [EMAIL PROTECTED]
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
______________________________________________
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and provide commented, minimal, self-contained, reproducible code.
