Pascal Oettli kridox at ymail.com
Thu Jul 5 03:49:31 CEST 2012

```Hello,

A short code to include real monthly calendar to your data, similar to
the one inside NCEP2 reanalysis.

library(ncdf)

lon <- seq(from=140.0251, to=146.6751, length.out=241)
lat <- seq(from=-38.975, to=-31.025, length.out=160)
x=dim.def.ncdf("Lon","degreesE",as.double(lon))
y=dim.def.ncdf("Lat","degreesN",as.double(lat))

y1 = 1800        # start of the period
y2 = 2012        # end of the period

year <- seq(y1,y2,1)
day <-
c(31,28,31,30,31,30,31,31,30,31,30,31)%*%matrix(1,1,length(year));
day[2,leap.year(year)] <- 29; day <- as.vector(day)
hour <- day*24; hour <- c(hour[1],cumsum(hour[1:length(hour)-1]))
year <- rep(year,each=12)

syntime <- hour[year==1968] #change the year or change this line to
include more years
t=dim.def.ncdf("Time","hours since 1800-1-1 00:00:00",syntime,unlim=TRUE)

And your "mrain" matrix should have 3 dimensions (lon x lat x time),
before to save it as a NetCDF file.

Regards.

Le 04/07/2012 23:13, Jun Chen a écrit :
>
> Hi Pascal,
>         I think I figure it out.
>         By doing the following, I can made "lon" & "lat" become a class of dim.ncdf:
>          lon <- seq(from=140.0251, to=146.6751, length.out=241)
>          lat <- seq(from=-38.975, to=-31.025, length.out=160)
>          x=dim.def.ncdf("Lon","degreesE",as.double(lon))
>           y=dim.def.ncdf("Lat","degreesN",as.double(lat))
>
>        However, after running the script, there is a error I really unable to understand:
>           error at data.frame(..., check.names = FALSE) :
>           parameter value mean different rows 0, 31981
>
>        If you can understand what the problem is, please as kind as offer me a direction.
>
>
>
> Many thanks,
> Jun
>
>
>
>
>> Date: Wed, 4 Jul 2012 10:39:29 +0100
>> From: kridox at ymail.com
>> To: chenshong at hotmail.com
>> CC: r-help at r-project.org
>>
>> Hello,
>>
>> Following lines are wrong:
>>> x=dim.def.ncdf("Lon","degreesE",140.0251:146.6751)
>>> y=dim.def.ncdf("Lat","degreesN",(-31.025):(-38.975))
>>
>> You have 241 longitudes and 160 latitudes.
>> lon <- seq(from=140.0251, to=146.6751, length.out=241)
>> lat <- seq(from=-38.975, to=-31.025, length.out=160)
>>
>> Regards
>>
>>
>>
>> ----- Mail original -----
>> De : Jun Chen <chenshong at hotmail.com>
>> À : r-help at r-project.org
>> Cc :
>> Envoyé le : Mercredi 4 juillet 2012 10h52
>>
>>
>> Dear All,
>>            I am a research student in environment. I have only little programming knowledge. I am currently doing the last project about rainfall impact on ground water quality in an area. It happens that I have to use R to read rainfall data (3 dimension) from ASC file (*.asc), and then write them into one NCDF file (*.nc).
>>
>>            I have been working very hard on study R, but I still can not fix the problem. Could someone please as kind as point out that what the problems are in my R script?
>>
>>          Firstly, this is an example of data in asc file:
>>                      NCOLS      241
>>
>>                      NROWS      160
>>
>>                      XLLCORNER    140.00012207031
>>
>>                      YLLCORNER  -39.000000000000
>>
>>                      CELLSIZE    0.50000000000000E-01
>>
>>                      NODATA_VALUE  -99.00000
>>
>>                      166.30  160.87  155.23  149.33  143.83  138.52  133.29  128.34  123.76  119.21
>>
>>                      115.06  110.90  107.22  103.69  100.40  97.29  94.58  92.15  90.00  87.91
>>
>>                      86.20  84.57  83.22  81.94  81.11  80.38  79.37  78.73  79.70  79.62
>>            -----------------------------------------------------------------------------------------------------------------------
>>
>>
>>
>>            And then this is the script I wrote:
>>
>> setwd("E:/grid")
>>
>> #defining dimension
>>
>> x=dim.def.ncdf("Lon","degreesE",140.0251:146.6751)
>>
>> y=dim.def.ncdf("Lat","degreesN",(-31.025):(-38.975))
>>
>> t=dim.def.ncdf("Time","1968-01",1:12,unlim=TRUE)
>>
>>
>>
>> #setup variable
>>
>> varmr=var.def.ncdf("mr","mm",list(x,y,t),-99.00,
>>
>> longname="monthly rainfall")
>>
>>
>> #create ncdf file
>>
>> ncnew=create.ncdf("rainfall.nc", varmr)
>>
>>
>>
>> files=list.files(pattern=".asc")
>>
>> mrain=matrix(0:0,0,3)
>>
>>
>> for(i in files)
>>
>>
>>    mrain=cbind(mrain,rainfall)
>>
>> }
>>
>> put.var.ncdf(ncnew, mrain)
>>
>>
>> close.ncdf(ncnew)
>>
>> -------------------------------------------------------------------------------
>>
>> [[elided Hotmail spam]]
>>
>>
>>
>>
>>
>> Many thanks,
>> Jun
>>
>>
>>
>>
>>      [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>

```