R help - Jun 2003 - cut.POSIXct problem

Dear all

I would like to aggregate a data frame in a three minute interval. I have a time
vector:
> str(cas.param)
`POSIXct', format: chr [1:181] "2003-06-12 09:00:00"
"2003-06-12 09:01:00"
"2003-06-12 09:02:00" 

and I want to turn it into a factor by cut. It works if I want to break it in
let say
hours
> str(cut(cas.param,breaks="hour"))
 Factor w/ 3 levels "2003-06-12 ..",..: 1 1 1 1 1 1 1 1 1 1 .

But if i tried to do similar task but to construct three minutes intervals with
a
vector of cut points it gives me an error
> cut(cas.param,breaks=seq(min(cas.param),max(cas.param), by="3
mins"))
Error in sort(breaks) : `x' must be atomic

however
> str(seq(min(cas.param),max(cas.param), by="3 mins"))
`POSIXct', format: chr [1:61] "2003-06-12 09:00:00"
"2003-06-12 09:03:00"
"2003-06-12 09:06:00"

works.

So it is definitely my lack of understanding how to implement a vector of cut 
points (constructed by seq()), to break parameter of cut() function.

Please can you give me any hints?

R 1.7.0, Windows NT

Thanks a lot

Petr Pikal
petr.pikal at precheza.cz
p.pik at volny.cz

This works in R 1.7.1: please upgrade.

[That's assuming that your sequence actually covers the data: you need to
go beyond max(cas.param) to be sure, and it looks to me that with 
right=FALSE and include.lowest-FALSE the breaks never will cover the 
data.]


On Tue, 17 Jun 2003, Petr Pikal wrote:
> Dear all
> 
> I would like to aggregate a data frame in a three minute interval. I have a
time
> vector:
> 
> > str(cas.param)
> `POSIXct', format: chr [1:181] "2003-06-12 09:00:00"
"2003-06-12 09:01:00"
> "2003-06-12 09:02:00" 
> 
> and I want to turn it into a factor by cut. It works if I want to break it
in let say
> hours
> 
> > str(cut(cas.param,breaks="hour"))
>  Factor w/ 3 levels "2003-06-12 ..",..: 1 1 1 1 1 1 1 1 1 1 .
> 
> But if i tried to do similar task but to construct three minutes intervals
with a
> vector of cut points it gives me an error
> 
> > cut(cas.param,breaks=seq(min(cas.param),max(cas.param), by="3
mins"))
> Error in sort(breaks) : `x' must be atomic
> 
> however
> 
> > str(seq(min(cas.param),max(cas.param), by="3 mins"))
> `POSIXct', format: chr [1:61] "2003-06-12 09:00:00"
"2003-06-12 09:03:00"
> "2003-06-12 09:06:00"
> 
> works.
> 
> So it is definitely my lack of understanding how to implement a vector of
cut
> points (constructed by seq()), to break parameter of cut() function.
> 
> Please can you give me any hints?
> 
> R 1.7.0, Windows NT
> 
> Thanks a lot
> 
> Petr Pikal
> petr.pikal at precheza.cz
> p.pik at volny.cz
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://www.stat.math.ethz.ch/mailman/listinfo/r-help
> 
-- 
Brian D. Ripley,                  ripley at 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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