[R-sig-Geo] getting data from an nc file

[Alexander Ilich]

HDF Viewer<https://www.hdfgroup.org/downloads/hdfview/> can be a good way to look at the structure of nc files to see where different information is stored in the file.
________________________________
From: R-sig-Geo <r-sig-geo-bounces using r-project.org> on behalf of Nick Wray <nickmwray using gmail.com>
Sent: Wednesday, November 9, 2022 5:53 AM
To: r-sig-geo using r-project.org <r-sig-geo using r-project.org>
Subject: [R-sig-Geo] getting data from an nc file

Hello

I am trying to get rainfall data from the UK chess-met site

https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcatalogue.ceh.ac.uk%2Fdatastore%2Feidchub%2F2ab15bf0-ad08-415c-ba64-831168be7293%2Fprecip%2F&data=05%7C01%7Cailich%40usf.edu%7C39cfc2a140934dc323d408dac240b9c0%7C741bf7dee2e546df8d6782607df9deaa%7C0%7C0%7C638060296454914830%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=AJ5Q%2BWYYGxbXJZjHxisFdGAAomjtIWn95k5r9vtXniw%3D&reserved=0

and here there are a large number of nc files eg

"chess-met_precip_gb_1km_daily_20150101-20150131.nc"

I�ve found various sources on the net for opening nc files, and getting the
data but when I try instructions like

nc_data<-nc_open("chess-met_precip_gb_1km_daily_20150101-20150131.nc")

lon <- ncvar_get(nc_data, "lon")

lon



the code works but all I get is a series of element numbers and no data:

[,1]     [,2]     [,3]     [,4]     [,5]     [,6]     [,7]     [,8]     [,9]
[,10]    [,11]    [,12]

          [,13]    [,14]    [,15]    [,16]    [,17]    [,18]    [,19]
[,20]    [,21]    [,22]    [,23]    [,24]



And similarly for latitude

But if I open the nc file as a raster I get a raster precipitation plot of
Great Britain, which rather suggests that the lat and long values are in
there somewhere

Can anyone help with getting the actual data sets out of an nc file?

Thanks Nick Wray

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