[R-sig-Geo] Convert ncdf data to dataframe
Stachelek, Joseph
jstachel at sfwmd.gov
Thu Jun 2 15:20:39 CEST 2016
Hi Milu,
I would suggest reading your .nc file directly into a raster object using the `raster` package.
###
library(raster)
ncname <- ("/file_path")
ncfname <- paste(ncname, ".nc", sep = "")
r <- raster::raster(ncfname) # use raster::stack() if more than one "layer"
###
I have suggested that the author of the `ncdf4` package (David Pierce) make note of this easier way to load .nc files in the `ncdf4` documentation. If you need the coordinates of each raster cell you might take a look at the instructions here:
http://gis.stackexchange.com/questions/142156/r-how-to-get-latitudes-and-longitudes-from-a-rasterlayer
Joseph Stachelek
-----Original Message-----
From: R-sig-Geo [mailto:r-sig-geo-bounces at r-project.org] On Behalf Of Miluji Sb
Sent: Thursday, June 02, 2016 4:43 AM
To: R-sig-geo mailing list <r-sig-geo at r-project.org>
Subject: [R-sig-Geo] Convert ncdf data to dataframe
Dear all,
I have used the following code to read in a ncdf file
library(chron)
library(lattice)
library(ncdf4)
library(data.table)
ncname <- ("/file_path")
ncfname <- paste(ncname, ".nc", sep = "")
dname <- "ssl" # note: tmp means temperature (not temporary)
ncin <- nc_open(ncfname)
print(ncin)
The attributes of the file are:
4 variables (excluding dimension variables):
double longitude[row]
long_name: longitude
units: degrees_east
standard_name: longitude
double latitude[row]
long_name: latitude
units: degrees_north
standard_name: latitude
double ssl[col,row]
long_name: storm surge level
units: m
_FillValue: -99999
scale_factor: 1
add_offset: 1
float RP[col]
long_name: return period
units: yr
Contents: The RPs have been estimated following the Peak Over
Threshold Method (see reference below)
Starting date: 01-Dec-2009
End date: 30-Nov-2099 21:00:00
2 dimensions:
col Size:8
row Size:2242
I would like to convert the data into a dataframe by longitude and
latitude. Is that possible? Thank you!
Sincerely,
Milu
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