grib

README

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GRIB2 Golang parser application and library

Parser and library for grib2 file format.

Forked from github.com/analogic/grib which is now abandoned by the author (see comment on my pull request).

Usage

Install by typing

go get -u github.com/nilsmagnus/grib

Application Usage:

$ grib -h 

Usage of grib:
 -category int
   	Filters on Category within discipline. -1 means all categories (default -1)
 -dataExport
   	Export data values. (default true)
 -discipline int
   	Filters on Discipline. -1 means all disciplines (default -1)
 -export int
   	Export format. Valid types are 0 (none) 1(print discipline names) 2(print categories) 3(json) 
 -file string
   	Grib filepath
 -latMax int
   	Maximum latitude multiplied with 100000. (default 36000000)
 -latMin int
   	Minimum latitude multiplied with 100000.
 -longMax int
   	Maximum longitude multiplied with 100000. (default 9000000)
 -longMin int
   	Minimum longitude multiplied with 100000. (default -9000000)
 -maxmsg int
   	Maximum number of messages to parse. Does not work in combination with filters. (default 2147483647)
 -operation string
   	Operation. Valid values: 'parse', 'reduce'. (default "parse")
 -reducefile string
   	Destination for reduced file. (default "reduced.grib2")

Examples:

Reduce input file to default output-file with discipline 0 (Meteorology):

grib -operation reduce -file testdata/reduced.grib2 -discipline 0

Filter on area on size of norway+sweden, output to json:

grib -file testdata/gfs.t00z.pgrb2.2p50.f003  -latMin 57000000 -latMax 71000000 -longMin 4400000 -longMax 32000000 -export 3

Filter on temperature only:

grib -file testdata/gfs.t00z.pgrb2.2p50.f003 -discipline 0 -category 0 

Library examples

Have a look at 'main.go' for main usage.

What works?

• basic binary parsing of GRIB2 GFS files from NOAA
• implemented only "Grid point data - complex packing and spatial differencing"
• Parsing Data3 type
• Parsing Data0 type (Thanks to Cyrille Meichel)

Development

Dependencies

grib itself has no dependencies and wants to stay that way to keep it simple. Therefore, there is no dep/glide and no dependency-configuration-files.

Build

Grib uses make to build. You probably need go-lint installed in order to build.

To build, simply type

$ make

to test:

$ make test

TODOs

• Support different types of grids, not only grid0
• Support different types of products, not only product0
• Tests for reduction
• Tests for reading all sections

Contributors

• "analogic", https://github.com/analogic
• Cyrille Meichel, https://github.com/landru29
• Nils Larsgård, https://github.com/nilsmagnus

Help appreciated

Feel free to fork and submit pull requests or simply create issues for improvements :)

Grib Documentation

Grib specification:

http://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc.shtml

Documentation from noaa.gov :

http://www.nco.ncep.noaa.gov/pmb/docs/on388/

Daily grib2 files from NOAA can be found at

http://www.ftp.ncep.noaa.gov/data/nccf/com/gfs/prod/