[R] reading dataset

Pascal Oettli kridox at ymail.com
Thu Mar 27 14:38:42 CET 2014


Hi,

Maybe I wasn't clear enough.

Day 01   precip  map of 180x140
Day 01   rstn     map of 180x140
Day 01   flag      map of 180x140
Day 02   precip  map of 180x140

And so on

HTH
Pascal

On Thu, Mar 27, 2014 at 10:14 PM, Frede Aakmann Tøgersen
<frtog at vestas.com> wrote:
> No you're not right as far as I can tell from the read_v1100r2.f90 fortran code you can find in the download folder.
>
> For day 1 in 1961 I think that prcp = ccc[1:25200], rstn = ccc[25201:50400], and rsnw = ccc[50401:75600] and the same rule applies to the following days with appropriate indices.
>
> Have a look at this (I think -99.9 is value for missing values so set these to NA):
>
> ccc <-readBin("APHRO_MA_050deg_V1101R2.1961", numeric(), n=1e8, size=4, signed=TRUE, endian='little')
>
> n <- 180
> m <- 140
> recl <- n*m # = 25200
>
> ## calculate some indices for day 1 and 2
> for (i in 1:6){
>     strt <- (i - 1)*recl + 1
>     stp <- strt + recl - 1
>     print(c(strt, stp))
> }
>
> ## for day 1 in 1961
> prcp <- ccc[1:25200]
> prcp[prcp < -90] <- NA
> dim(prcp) <- c(n, m)
> image(prcp)
>
> rstn <- ccc[25201:50400]
> rstn[rstn < -90] <- NA
> dim(rstn) <- c(n, m)
> image(rstn)
>
> rsnw <- ccc[50401:75600]
> rsnw[rsnw < -90] <- NA
> dim(rsnw) <- c(n, m)
> image(rsnw)
>
>
>
> I will leave it to you to interpret rstn and rsnw in regards to prcp.
>
>
>
>
> Yours sincerely / Med venlig hilsen
>
>
> Frede Aakmann Tøgersen
> Specialist, M.Sc., Ph.D.
> Plant Performance & Modeling
>
> Technology & Service Solutions
> T +45 9730 5135
> M +45 2547 6050
> frtog at vestas.com
> http://www.vestas.com
>
> Company reg. name: Vestas Wind Systems A/S
> This e-mail is subject to our e-mail disclaimer statement.
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>
>> -----Original Message-----
>> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
>> On Behalf Of eliza botto
>> Sent: 27. marts 2014 13:26
>> To: Pascal Oettli
>> Cc: r-help at r-project.org
>> Subject: Re: [R] reading dataset
>>
>> Dear Pascal,
>> Thanks for your reply. From your answer I perceived that if followings are
>> first three elements of a file
>> > dput(ccc[1:3])
>> c(0.15912090241909, 0.167244642972946, 0.192471280694008)
>> then 0.15912090241909 is precipitation magnitude , 0.167244642972946 is
>> RSTN and 0.192471280694008 is flag value.Did i get it right?
>> Eliza
>>
>>
>>
>> > From: kridox at ymail.com
>> > Date: Thu, 27 Mar 2014 12:39:30 +0900
>> > Subject: Re: [R] reading dataset
>> > To: eliza_botto at hotmail.com
>> > CC: r-help at r-project.org
>> >
>> > Hello,
>> >
>> > Some hints:
>> >    - for the year 1961, the total number of values is 27594000,
>> >    - there are 180 longitudes and 140 latitudes,
>> >    - there are 365 days,
>> >    - there are 3 variables,
>> >
>> > Compare the total number of values and the result of (180 x 140 x 365 x 3).
>> >
>> > The order is "precip", "rstn", "flag", "precip", "rstn", "flag",
>> > "precip", "rstn", "flag"...
>> >
>> > Hope this helps,
>> > Pascal
>> >
>> > On Thu, Mar 27, 2014 at 9:45 AM, eliza botto <eliza_botto at hotmail.com>
>> wrote:
>> > > Dear useRs,
>> > > A similar question has previously been asked by another user
>> (https://stat.ethz.ch/pipermail/r-sig-geo/2011-September/012791.html) but
>> i'll try to discuss it from another angle. Its about data reading. I am trying to
>> read to read a data-set APHRO_MA_050deg_V1101R2.1961.gz from
>> http://www.chikyu.ac.jp/precip/cgi-
>> bin/aphrodite/script/aphrodite_cgi.cgi/download?file=%2FV1101R2%2FAPH
>> RO_MA%2F050deg.
>> > > I copied the command from previous post which is
>> > > ccc <-readBin("APHRO_MA_050deg_V1101R2.1961", numeric(), n=1e8,
>> size=4, signed=TRUE, endian='little')
>> > > Followings are what I know about the structure of data set. The file
>> contains daily fields for 365 days. These daily fields are arranged according to
>> the Julian calendar.  Daily
>> > > fields (data arrays) contain information on the precipitation amount and
>> > > ratio of 0.05-degree cells containing a rain gauge.  In the case the given
>> file which is a
>> > > 0.5-degree grid file, each field consists of a data array with longitude
>> > > by latitude dimensions of  180 x 140 elements for APHRO_MA.
>> > >  The first element is a cell at the southwest corner centered at [60.25E,
>> 14.75S], the second
>> > > is a cell at [60.75E, 14.75S], ..., the 180th is a cell at [149.75E,
>> > > 14.75S], and the 181st is a cell at [60.25E, 14.25S]. The data files are
>> written in PLAIN DIRECT ACCESS BINARY.  In each daily field, the array for
>> precipitation comes first, followed by
>> > > information on the rain gauge. Each element (both precipitation and
>> > > rain gauge information) is written as a 4-byte floating-point number
>> > > in little endian byte order.  Users should swap the byte order to
>> > > big endian if necessary.  There are no 'space', 'end of record', or
>> > > 'end of file' marks in between.  As it says that precipitation data is in the
>> form of array which comes first, followed by the information on rain gauge,
>> how do I know which element is precipitation data and which is the
>> information of the rain gauge?Thankyou very  much in advance
>> > >
>> > > Eliza
>> > >         [[alternative HTML version deleted]]
>> > >
>> > > ______________________________________________
>> > > R-help at r-project.org mailing list
>> > > 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.
>> >
>> >
>> >
>> > --
>> > Pascal Oettli
>> > Project Scientist
>> > JAMSTEC
>> > Yokohama, Japan
>>
>>       [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> 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.



-- 
Pascal Oettli
Project Scientist
JAMSTEC
Yokohama, Japan




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