Re: [R] density() returns a density function that does not add up to 1

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From: A.J. Rossini (rossini@blindglobe.net)
Date: Sat 31 Aug 2002 - 06:09:03 EST 

Message-id: <87lm6ohzxc.fsf@jeeves.blindglobe.net>

>>>>> "jonathan" == Jonathan Li <jonqli@labs.agilent.com> writes:

    jonathan> Dear R users,
    jonathan> I ran into this curious problem:

>> d <- rnorm(100)
>> d.density <- density(d)
>> sum( d.density$x * d.density$y)
    jonathan> [1] 2.517502

whoops, you probably want something like:

> sum( diff(d.density$x) * d.density$y)
[1] 1.000950

instead, for a crude integration (and yes, it throws a warning). 

-- 
A.J. Rossini				Rsrch. Asst. Prof. of Biostatistics
U. of Washington Biostatistics		rossini@u.washington.edu	
FHCRC/SCHARP/HIV Vaccine Trials Net	rossini@scharp.org
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