[R] about netcdf files

Roy Mendelssohn - NOAA Federal roy.mendelssohn at noaa.gov
Tue Jul 26 22:52:42 CEST 2016


Hi Lily:

I doubt the mail-list would pass through the netcdf file. Instead, could you do the following, and post the results:

library(ncdf4
pre1 = nc_open('sample_precip_daily.nc')
str(pre1)
nc_close(pre1)

I have a feeling you haven't worked much with netcdf files. I will try to find a tutorial also to help you along.

Thanks,

-Roy

> On Jul 26, 2016, at 12:07 PM, lily li <chocold12 at gmail.com> wrote:
> 
> Thanks for your reply. But it says "Error in (function (classes, fdef,
> mtable)):
> unable to find an inherited method for function 'brick' for signature
> 'ncdf4' "
> 
> The dataset is attached. It contains daily precipitation data for 20 years,
> within a rectangle, so that there are several grid points. I use the code
> to open it, but don't know how to get csv files, while each file contains
> continuous daily precipitation data for each grid cell.
> pre1 = nc_open('sample_precip_daily.nc')
> pre1
> pre1_rd = ncvar_get(pre1, 'precipitation')
> nc_close(pre1)
> 
> Thanks for your help.
> 
> On Tue, Jul 26, 2016 at 4:08 AM, Jon Skoien <jon.skoien at jrc.ec.europa.eu>
> wrote:
> 
>> You could try with the brick function from the raster package.
>> 
>> bvar = brick(netcdfName)
>> 
>> This uses the ncdf4 functions for opening and reading the netcdf, but
>> makes it easier to extract data for each day:
>> 
>> p1 = rasterToPoints(bvar[[1]])
>> and write p1 to csv.
>> 
>> Best,
>> Jon
>> 
>> 
>> 
>> On 7/26/2016 6:54 AM, lily li wrote:
>> 
>>> Hi all,
>>> 
>>> I have a problem in opening netcdf files. If one netcdf file contains
>>> longitude, latitude, and daily precipitation. How to relate each
>>> precipitation record to its associated location, and export them as csv
>>> files? Thanks.
>>> 
>>> I just use nc_open(), ncvar_get(), but it is not very helpful. Thanks for
>>> any ideas.
>>> 
>>>        [[alternative HTML version deleted]]
>>> 
>>> ______________________________________________
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>>> PLEASE do read the posting guide
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>>> and provide commented, minimal, self-contained, reproducible code.
>>> 
>>> 
>> --
>> Jon Olav Skøien
>> Joint Research Centre - European Commission
>> Institute for Space, Security & Migration
>> Disaster Risk Management Unit
>> 
>> Via E. Fermi 2749, TP 122,  I-21027 Ispra (VA), ITALY
>> 
>> jon.skoien at jrc.ec.europa.eu
>> Tel:  +39 0332 789205
>> 
>> Disclaimer: Views expressed in this email are those of the individual and
>> do not necessarily represent official views of the European Commission.
>> 
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
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> and provide commented, minimal, self-contained, reproducible code.

**********************
"The contents of this message do not reflect any position of the U.S. Government or NOAA."
**********************
Roy Mendelssohn
Supervisory Operations Research Analyst
NOAA/NMFS
Environmental Research Division
Southwest Fisheries Science Center
***Note new address and phone***
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Santa Cruz, CA 95060
Phone: (831)-420-3666
Fax: (831) 420-3980
e-mail: Roy.Mendelssohn at noaa.gov www: http://www.pfeg.noaa.gov/

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