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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of vittorio
Sent: Sunday, April 09, 2006 6:12 AM
To: r-help@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, venerdì 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: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Vittorio
Sent: Friday, April 07, 2006 11:38 AM
To: r-help@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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