[R] NOAA .grb2 files

Roy Mendelssohn - NOAA Federal roy@mende|@@ohn @end|ng |rom no@@@gov
Sat Sep 5 01:11:04 CEST 2020


Hi Philip:

It would help if you gave the complete script you are trying to run,  and the name of the file.  

for those unfamiliar with all this,  Philip has already downloaded the grib2 file,  either using rNOMADS or directly from the NOAA website,  and the function he is calling reads the data from that grib2 file by wrapping a system call to a C-program called wgrib2.  And if you don't know about grib2 files,  they are highly compressed files of fields,  using bit-packing to do the compression. Forecast grib2 files usually have a plethora of fields,  for example since I don't know exactly which  NOAA Rapid Refresh model files he obtain,  looking at the inventory of one possible such file,  see:

https://www.nco.ncep.noaa.gov/pmb/products/rap/rap.t00z.awp252pgrbf00.grib2.shtml

Usually given this,  only one or a couple of fields at a time are unpacked,  unless you have a large computer.  Since no example script was given,  it is impossible to tell if he is trying to read in the entire grib2 file or what.  And each expanded array in R will be much much bigger than the equivalent in grib2.

-Roy



> On Sep 4, 2020, at 3:32 PM, Philip <herd_dog using cox.net> wrote:
> 
> I’m trying to download NOAA Rapid Refresh model weather data but I keep getting the error message below.  Do I just need a computer with more memory?
> 
> Philip
> 
> ***********************************************************************************************************************************************
> Error in paste(gsub("\"", "", csv.str), collapse = ",") : 
>  could not allocate memory (994 Mb) in C function 'R_AllocStringBuffer' 
> 	[[alternative HTML version deleted]]
> 
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**********************
"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
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Santa Cruz, CA 95060
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e-mail: Roy.Mendelssohn using noaa.gov www: https://www.pfeg.noaa.gov/

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