[R] Aggregating daily rainfall raster data to bimontly data

[John Wasige]

Thanks Jim!

Do you have an idea on how I can go about getting bi-monthly (twice a
month) results for the month with 28, 29, 30 and 31 daily observations?

Thanks for your help

John.

On Sun, Apr 5, 2015 at 11:25 PM, Jim Lemon <drjimlemon at gmail.com> wrote:

> Hi John,
> One way is to create an index variable that will divide your data into the
> appropriate intervals. There are a number of ways to do this. Say you want
> the "two month" version of bimonthly and you have a date variable
> ("raindate") for each observation like "1982-01-01".
>
> date_order<-paste(rep(month.abb,30),rep(1982:2011,each=12),sep="")
>
> month_index<-factor(format(as.Date(raindate,"%Y-%m-%d"),"%b%Y"),levels=date_order)
>
> You can then subset the raster matrices by "month_index" and average them
> for each group
>
> Jim
>
> On Mon, Apr 6, 2015 at 3:08 AM, Jeff Newmiller <jdnewmil at dcn.davis.ca.us>
> wrote:
>
>> Please stop posting using HTML (as the Posting Guide warns you), and
>> follow John Kane's advice. Your reply below is not helping us understand as
>> well as you seem to think it should.
>>
>> ---------------------------------------------------------------------------
>> Jeff Newmiller                        The     .....       .....  Go
>> Live...
>> DCN:<jdnewmil at dcn.davis.ca.us>        Basics: ##.#.       ##.#.  Live
>> Go...
>>                                       Live:   OO#.. Dead: OO#..  Playing
>> Research Engineer (Solar/Batteries            O.O#.       #.O#.  with
>> /Software/Embedded Controllers)               .OO#.       .OO#.
>> rocks...1k
>>
>> ---------------------------------------------------------------------------
>> Sent from my phone. Please excuse my brevity.
>>
>> On April 5, 2015 9:52:18 AM PDT, John Wasige <johnwasige at gmail.com>
>> wrote:
>> >Thanks Bert,
>> >
>> >The structure of the data is a raster stack with nraw=867, Ncol=995
>> >
>> >Rgds John
>> >
>> >
>> >On Sun, Apr 5, 2015 at 6:39 PM, Bert Gunter <gunter.berton at gene.com>
>> >wrote:
>> >
>> >> See ?tapply
>> >>
>> >> However, as John said, without knowing the structure of your data, it
>> >> is impossible to provide a guaranteed recipe. For example, does the
>> >> data structure contain date information? -- it would be difficult
>> >(but
>> >> not impossible depending on data structure) to aggregate by calendar
>> >> (bi-monthly, depending on your meaning of "bi") without knowing the
>> >> months. Aggregating by every n days would be easy, but that's
>> >probably
>> >> not what you want.
>> >>
>> >> Cheers,
>> >> Bert
>> >>
>> >> Bert Gunter
>> >> Genentech Nonclinical Biostatistics
>> >> (650) 467-7374
>> >>
>> >> "Data is not information. Information is not knowledge. And knowledge
>> >> is certainly not wisdom."
>> >> Clifford Stoll
>> >>
>> >>
>> >>
>> >>
>> >> On Sun, Apr 5, 2015 at 9:13 AM, John Kane <jrkrideau at inbox.com>
>> >wrote:
>> >> > Someone might if they had any idea of what the data actually looked
>> >like
>> >> and what you are trying to do. The 'bimonthly' for example, is
>> >ambiguous in
>> >> English; do you mean every two months or twice a month?
>> >> >
>> >> > Have a look at
>> >https://github.com/hadley/devtools/wiki/Reproducibility
>> >> and
>> >>
>> >
>> http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example
>> >> with special attention to dput() as a method of supplying sample data
>> >to
>> >> the help list.
>> >> >
>> >> > John Kane
>> >> > Kingston ON Canada
>> >> >
>> >> >
>> >> >> -----Original Message-----
>> >> >> From: johnwasige at gmail.com
>> >> >> Sent: Sun, 5 Apr 2015 11:34:30 +0200
>> >> >> To: r-help at r-project.org
>> >> >> Subject: [R] Aggregating daily rainfall raster data to bimontly
>> >data
>> >> >>
>> >> >> Dear community,
>> >> >>
>> >> >> I have daily rainfall raster data for 30 years (1982_2011). I
>> >would like
>> >> >> to
>> >> >> aggregate daily to bimonthly raster data. Could somebody kindly
>> >help on
>> >> >> how
>> >> >> to go about it!
>> >> >>
>> >> >> Thanks for your help
>> >> >>
>> >> >> --
>> >> >> John
>> >> >>
>> >> >>       [[alternative HTML version deleted]]
>> >> >>
>> >> >> ______________________________________________
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>> >> >> PLEASE do read the posting guide
>> >> >> http://www.R-project.org/posting-guide.html
>> >> >> and provide commented, minimal, self-contained, reproducible code.
>> >> >
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>> >> > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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>> >> > PLEASE do read the posting guide
>> >> http://www.R-project.org/posting-guide.html
>> >> > and provide commented, minimal, self-contained, reproducible code.
>> >>
>> >
>> >       [[alternative HTML version deleted]]
>> >
>> >______________________________________________
>> >R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> >https://stat.ethz.ch/mailman/listinfo/r-help
>> >PLEASE do read the posting guide
>> >http://www.R-project.org/posting-guide.html
>> >and provide commented, minimal, self-contained, reproducible code.
>>
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>

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