Just strip off the hours component of the dates, then take a subset of the data
where the hour is <= 12.
I did not execute this, so you might need to change it a bit:
hours <- as.integer(format(dates(base),"%H"))
new.data <- base[hours <= 12,]
aggregate(new.data,by=list(as.factor(format(dates(new.data),"%Y%m%d"))),mean,na.rm=T)
-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch [mailto:r-help-bounces at
stat.math.ethz.ch] On Behalf Of vittorio
Sent: Sunday, April 09, 2006 6:12 AM
To: r-help at stat.math.ethz.ch
Subject: Re: [R] (IT WAS) Aggregating an its series
Thanks for the brilliant solution.
***AGAIN***
Now - just to go deeper into the **same subject** on which I'm really
supposed to work very soon - if I want to aggregate by date only data, say,
before noon (12.00.00) what should I do?
Ciao
Vittorio
Alle 16:13, venerd? 07 aprile 2006, Whit Armstrong ha
scritto:>
aggregate(base,by=list(as.factor(format(dates(base),"%Y%m%d"))),mean,na.
> rm=T)
>
>
> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Vittorio
> Sent: Friday, April 07, 2006 11:38 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Aggregating an its series
>
> I'm using a very long irregular time-series of air temperature and
> relative humidity of this kind (this is an extract only)
>
> its.format("%
> Y%d%m %X)
>
> > base
>
> T H
> 20020601 12.00.00 27.1 47
> 20020601 15.00.00 29.1 39
> 20020601 18.00.00 27.4 39
> 20020601 21.00.00 24.0 40
> 20020602 0.00.00 22.0 73
> 20020602 3.00.00 19.2 49
> 20020602 6.00.00 19.5 74
> 20020602 9.00.00 24.8 45
> 20020602 12.00.00 27.7 NA
> 20020602 15.00.00 29.2 39
> 20020602 18.00.00 27.2 44
> 20020602 21.00.00 23.9 50
> 20020603 0.00.00 21.0 75
> 20020603 3.00.00 19.6 65
> 20020603 6.00.00 19.8 71
> 20020603 9.00.00 23.2 67
> 20020603 12.00.00 24.9 65
> 20020603 15.00.00 21.7 74
> 20020603 18.00.00 22.8 63
> 20020603 21.00.00 21.2 75
> 20020604 0.00.00 18.0 91
>
> I would like to
> aggregate T and H by day and produce another its of this kind
>
> > aggr
>
> T H
> 20020601 NA NA
> 20020602 NA NA
> 20020603 NA NA
> 20020604 NA NA
>
> where the daily average of T and H (not counting the NA
> values) is is put in aggr.
>
> What is the quickest way to get this
> result?
>
> Thanks
>
> Vittorio
>
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