hwrf.regrib Namespace Reference

Describes regribbing operations using an algebraic structure. More...

Detailed Description

Describes regribbing operations using an algebraic structure.

This module provides an object-oriented interface to the low-level GRIB manipulation routines in produtil.gribop. It also sits on top of the produtil.datastore module, providing a means to grab GRIB files from Task and Product objects, processing them upon availability.

Classes
class	FixedLocation
	Represents a specific location on the earth as a latitude, longitude pair. More...
class	GRIB1Fetcher
	The GRIB1Fetcher is a GRIB1Op subclass that fetches a GRIB1 file from a RegribMany. More...
class	GRIB1File
	This subclass of GRIB1Op represents a GRIB1 file on disk that is ALREADY PRESENT. More...
class	GRIB1Op
	This subclass of GRIBOp produces GRIB1 files. More...
class	GRIB1Product
	This class represents a GRIB1 file produced by this workflow. More...
class	GRIB1Selector
	This object produces a GRIB1Op from a call to a Task object's Task.product. More...
class	GRIB2File
	This subclass of GRIB2Op represents a GRIB2 file on disk that is ALREADY PRESENT. More...
class	GRIB2Op
	This subclass of GRIBOp produces GRIB2 files, and can be converted to GRIB1 via obj*GRIB1 or obj.to_grib1(). More...
class	GRIB2Product
	This class represents a GRIB2 file that is produced by this workflow. More...
class	GRIBBase
	Base class for the regridding object tree. More...
class	GRIBGrid
	This class represents a GRIB1 or GRIB2 grid specification. More...
class	GRIBGridBase
	This abstract base class represents something that is able to produce a GRIBGrid object when make() is called. More...
class	GRIBGridCompute
	This class represents a GRIBGrid that must be computed from some other input, usually a GRIB file. More...
class	GRIBGridFetcher
	This class represents a GRIBGrid that is stored in a RegribMany object. More...
class	GRIBOp
	This is the abstract base class for all GRIB1 and GRIB2 files and operators. More...
class	GRIBSubsetter
	A GRIBBase that subsets GRIB files, keeping only certain parameters. More...
class	GRIBSubsetterFetcher
	This class grabs a GRIBSubsetter from a RegribMany object. More...
class	Regrib
	This is a helper class intended to be used internally by RegribMany. More...
class	RegribBase
	This is the abstract base class of Regrib and RegribMany and should not be instantiated directly. More...
class	RegribMany
	Runs regrib operations on many input times, sending output to an hwrf.gribtask.GRIBTask. More...
class	UpstreamGRIB1
	This subclass of GRIB1Op and UpstreamFile represents a GRIB1 file that is produced by an upstream workflow. More...

Functions
def	checkgrib (regrib, filename)
	Internal function for validating GRIB files. More...
def	action_grib1to2 (op, regrib, infile, args, kwargs)
	Converts GRIB1 file to GRIB2. More...
def	action_grib2to1 (op, regrib, infile, args, kwargs)
	Converts GRIB2 files to GRIB1. More...
def	action_grib1regridmerge (op, regrib, grid, in1, in2, kwargs)
	Performs regridding and merges two files in a single operation. More...
def	action_grbindex (op, regrib, ingrib, task=None, kwargs)
	Runs the grbindex program on a GRIB1 file. More...
def	action_grib1merge (op, regrib, in1, in2, kwargs)
	Merges two GRIB1 files that must already have the same grid. More...
def	action_grib1regrid (op, regrib, infile, ingrid, args, kwargs)
	Regrids a GRIB1 file. More...
def	action_grib1subset (op, regrib, infile, subsetter, args, kwargs)
	Subsets a GRIB1 file. More...
def	action_clatlon (op, regrib, name, center, nsres, ewres, nssize, ewsize, nscount, ewcount, scan, kwargs)
	Generates a latitude-longitude grid centered on a GRIB file or specified point. More...
def	clatlon
	Create a GRIBGridCompute that makes a lat-lon grid. More...
def	igrb1 (task, kwargs)
	This is a convenient alias for the GRIB1Selector constructor. More...

Variables
list	__all__
	List of symbols to export by "from hwrf.regrib import *". More...
int	GRIB1 = 1
	Constant used to represent a request to convert GRIB files to GRIB version 1. More...
int	GRIB2 = 2
	Constant used to represent a request to convert GRIB files to GRIB version 2. More...
int	GRIB_FILE_MIN_SIZE = 8
	Eight bytes: the minimum required size of a non-empty GRIB1 or GRIB2 file. More...
tuple	quarterDegree = GRIBGrid('Quarter_Degree_Grid_193','193',None)
	A special GRIBGrid representing grid 193, which is a quarter degree regular lat-lon grid the NCEP GFS model uses as output. More...

Function Documentation

def hwrf.regrib.action_clatlon	(		op,
			regrib,
			name,
			center,
			nsres,
			ewres,
			nssize,
			ewsize,
			nscount,
			ewcount,
			scan,
			kwargs
	)

Generates a latitude-longitude grid centered on a GRIB file or specified point.

This is an internal implementation function that should not be called directly. It queries the center object's nscenter and ewcenter properties to get the objects location. It then adds a border around that, creating a GRIB1 grid 255 grid specification centered on the center object.

Parameters

op	The GRIBBase operation running this funciton.
center	The GRIBBase operation on which to center the grid
regrib	a Regrib for data information
name	the name of the resulting grid, for storage in a RegribMany
nsres,ewres	GRIB1 grid 255 resolution information
nssize,ewsize	GRIB1 grid 255 size information, but in degrees. It will be converted to millidegrees for passing to underlying GRIB manipulation programs.
nscount,ewcount	Number of gridpoints in each direction, for the GRIB1 grid 255 information.
scan	GRIB1 grid 255 scanning mode byte
kwargs	Ignored

Returns

a new GRIBGrid for the new grid

Definition at line 1059 of file regrib.py.

Referenced by hwrf.regrib.action_grib1subset().

def hwrf.regrib.action_grbindex	(		op,
			regrib,
			ingrib,
			task = None,
			kwargs
	)

Runs the grbindex program on a GRIB1 file.

This is a low-level implementation function. It should not be called directly. This function adds a grbindex output to the specified input file's product, unless one is already available. Unlike most action_* functions, this one does not create a new GRIBFile or GRIBProduct, instead it modifies the existing one to add the location of the grbindex output.

Parameters

op	The GRIBBase operation running this funciton.
regrib	a Regrib for data information
ingrib	The input GRIBBase that represents the input file.
task	An hwrf.hwrftask.HWRFTask to provide the path to grbindex
kwargs	Ignored

Returns

ingrib

Definition at line 884 of file regrib.py.

def hwrf.regrib.action_grib1merge	(		op,
			regrib,
			in1,
			in2,
			kwargs
	)

Merges two GRIB1 files that must already have the same grid.

This is a low-level implementation function. It should not be called directly. This function is sent as a parameter to GRIB1Op to do a copygb merge (-xM) of two GRIB1 files to produce a single GRIB1 file. It requires that at least one of the files have a known grid, and if both have a known grid then their grids must mach.

Parameters

op	The GRIBBase operation running this funciton.
regrib	a Regrib for data information
in1,in2	The input GRIBGrid objects that provide filenames
kwargs	Ignored

Returns

The resulting GRIB1File, which may be in1, in2 or a new GRIB1File

Bug:

This function calls pwd and ls -l if things go wrong. It needs to use produtil.listing instead.

Definition at line 921 of file regrib.py.

def hwrf.regrib.action_grib1regrid	(		op,
			regrib,
			infile,
			ingrid,
			args,
			kwargs
	)

Regrids a GRIB1 file.

This is a low-level implementation function. It should not be called directly. This is sent as a parameter to GRIB1Op to convert a GRIB1 file from one grid to another. The output has a known grid, so it can be sent into an action_grib1merge.

Parameters

op	The GRIBBase operation running this funciton.
regrib	a Regrib for data information
infile	The input filename.
ingrid	Input GRIB1Grid that specifies the target grid.
args,kwargs	Ignored

Returns

a new GRIB1File for the output file

Definition at line 989 of file regrib.py.

def hwrf.regrib.action_grib1regridmerge	(		op,
			regrib,
			grid,
			in1,
			in2,
			kwargs
	)

Performs regridding and merges two files in a single operation.

This is a low-level implementation function. It should not be called directly. This function is sent as a parameter to GRIB1Op to do a copygb regrid AND merge in a single operation (one call to the copygb program). The grid argument is the target grid, and the in1 and in2 arguments are the input GRIB1 files.

Parameters

op	The GRIBBase operation running this funciton.
regrib	a Regrib for data information
in1,in2	The input filenames.
grid	The GRIBGrid that provides grid information.
kwargs	Ignored

Returns

a GRIB1File for the output file, which may be in1 or in2, or a new GRIB1File

Definition at line 828 of file regrib.py.

def hwrf.regrib.action_grib1subset	(		op,
			regrib,
			infile,
			subsetter,
			args,
			kwargs
	)

Subsets a GRIB1 file.

This is a low-level implementation function. It should not be called directly. It subsets a GRIB1 file infile using the given subsetter. The subsetter should have a list of strings accessible via subsetter.grib1sub. It should also have a name accessible through subsetter.subsetname. The wgrib -s output of infile is scanned. Any line in wgrib -s's output that contains the entirety of any line in the subsetter.grib1sub is retained. The subsetting is done via wgrib -i -grib (infile) -o (outfile).

Parameters

op	The GRIBBase operation running this funciton.
regrib	a Regrib for data information
infile	The input filename.
subsetter	A GRIBSubsetter that chooses the fields to keep.
args,kwargs	Ignored

Returns

a new GRIB1File for the output file

Definition at line 1020 of file regrib.py.

def hwrf.regrib.action_grib1to2	(		op,
			regrib,
			infile,
			args,
			kwargs
	)

Converts GRIB1 file to GRIB2.

This is a low-level implementation function. It should not be called directly. This function is sent as a parameter to GRIB1Op to produce a GRIB2 version of a GRIB1 file. It uses regrib.cnvgrib_g12 to perform the conversion.

Parameters

op	The GRIBBase operation running this funciton.
regrib	a Regrib for data information
infile	The input filename.
args,kwargs	Ignored

Returns

a new GRIB2File for the output file

Definition at line 776 of file regrib.py.

def hwrf.regrib.action_grib2to1	(		op,
			regrib,
			infile,
			args,
			kwargs
	)

Converts GRIB2 files to GRIB1.

This is a low-level implementation function. It should not be called directly. This function is sent as a parameter to GRIB2Op to produce a GRIB1 version of a GRIB2 file. It uses regrib.cnvgrib_g21 to do the conversion.

Parameters

op	The GRIBBase operation running this funciton.
regrib	a Regrib for data information
infile	The input filename.
args,kwargs	Ignored

Returns

a new GRIB1File for the output file

Warning

This is not used by any HWRF configuration and has not been tested in a while.

Definition at line 801 of file regrib.py.

def hwrf.regrib.checkgrib	(		regrib,
			filename
	)

Internal function for validating GRIB files.

This is a low-level implementation function. It should not be called directly. This checks a file to make sure it exists, is a regular file (or symlink to a regular file) and is large enough to plausibly contain some GRIB1 or GRIB2 data. Returns True for such plausible files and False otherwise. Does not open the file, and performs only a single stat. Uses errno ENOENT (no such file or directory) and ELOOP (too many symbolic links) to detect non-existence. Other exceptions will be passed to the caller.

Parameters

regrib	a regrib for logging information
filename	the name of the file of interest

Definition at line 731 of file regrib.py.

Referenced by hwrf.regrib.action_grib1merge(), hwrf.regrib.action_grib1regrid(), and hwrf.regrib.action_grib1regridmerge().

def hwrf.regrib.clatlon	(		center,
			res,
			size,
			n,
			scan = 136,
			name = None
	)

Create a GRIBGridCompute that makes a lat-lon grid.

Returns a GRIBGridCompute that will produce a lat-lon grid centered on the given object. The provided object must have nscenter and ewcenter properties that produce real lats and lons that are positive North and positive East. The res parameter is a two element array containing the resolution in degrees.

Parameters

name	the new grid's name
center	An object on which to center. Must have nscenter and ewcenter properties.
res	The GRIB1 grid 255 resolution information in a two-element array.
size	The size parameter is a two-element array containing the extent in degrees.
n	The n parameter contains the number of gridpoints.
scan	The "scan" parameter is the scanning mode parameter: 128 means E-W are reversed, 64 means N-S are reversed, and 32 means the data is transposed.

Note

All three, res, size and n, are two element arrays with the N-S value first and the E-W value second. These are turned into a GRIB1 grid 255 specification.

Definition at line 1334 of file regrib.py.

def hwrf.regrib.igrb1	(		task,
			kwargs
	)

This is a convenient alias for the GRIB1Selector constructor.

Parameters

task,kwargs

Passed to GRIB1Selector.__init__()

Definition at line 1956 of file regrib.py.

Variable Documentation

hwrf.regrib.__all__

Initial value:

= ['GRIBOp','GRIB2Op','GRIB1Op','GRIBGrid','GRIBSubsetter',
         'GRIB1Merge','Regrib','GRIB1','GRIB2','GRIB1File',
         'GRIB2File','UpstreamGRIB1','GRIB2Product','quarterDegree']

List of symbols to export by "from hwrf.regrib import *".

Definition at line 22 of file regrib.py.

hwrf.regrib.GRIB1 = 1

Constant used to represent a request to convert GRIB files to GRIB version 1.

Definition at line 28 of file regrib.py.

hwrf.regrib.GRIB2 = 2

Constant used to represent a request to convert GRIB files to GRIB version 2.

Definition at line 32 of file regrib.py.

hwrf.regrib.GRIB_FILE_MIN_SIZE = 8

Eight bytes: the minimum required size of a non-empty GRIB1 or GRIB2 file.

This size is chosen because it is not possible for a file to be smaller than this and still meet the GRIB standard. Realistically, the file should be much larger.

Definition at line 725 of file regrib.py.

hwrf.regrib.quarterDegree = GRIBGrid('Quarter_Degree_Grid_193','193',None)

A special GRIBGrid representing grid 193, which is a quarter degree regular lat-lon grid the NCEP GFS model uses as output.

Definition at line 1210 of file regrib.py.