Confusion in 'quantile' and getting rolling estimation of sample quantiles

There is no quantile method defined for zoo objects so it falls
through to the default method but that method does not work for zoo
objects.  Try this:

set.seed(123)
rn <- rnorm(500)
quantile(rn, 0.8)
quantile(coredata(zoo(rn)), 0.8)

In the second question the error message tells you what the problem
is.  FUN is supposed to be a function but a vector of numbers has been
supplied rather than a function.  Try:

uprange=rollapply(x,width=10,FUN=function(x)quantile(x,0.8),align='right')

On Sat, Jan 16, 2010 at 10:08 PM, Saji Ren <saji.ren at gmail.com> wrote:

Guys:

1).When I using the 'quantile' function, I get really confused. Here is
what
I met:

x<-zoo(rnorm(500,0,1))
quantile(x,0.8)

? ? 400
1.060258

c=rnorm(500,0,1)
quantile(c,0.8)

? ? ?80%
0.9986075

why do the results display different? Is that because of the different
type
of the class?

2).And I want to use the 'rollapply' function to compute a rolling
estimation of the sample quantile.
the command i used is below:

uprange=rollapply(x,width=10,FUN=quantile(x,0.8),align='right')

Here the 'x' is the one generated above in 1).
And the R told me:

"mistakes in match.fun(FUN) :
?'quantile(x, 0.8)' is not a function, character or symbol"

Can anyone help? Thank you in advanced.


-----
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Saji Ren
from Shanghai China
GoldenHeart Investment Group
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