*Scripts for parsing GrADS .ctl files
-Author: Takeshi Enomoto
-History:
18 Aug 2005 v0.3: bug fix. hours were obtained incorrectly
25 Feb 2005 v0.2: bug fixes. grads_time() now returns a useful array
22 Feb 2005 v0.1: first release
This suites consists of awk and ncl scripts.
*awk scripts
**scripts to read file meta information:
-dset.awk: returns the path to the data file
-title.awk: returns the title
-undef.awk: returns the undefined value
**scripts to read coordinates and their meta information:
-xdef.awk: returns x coordinates
-ydef.awk: returns y coordinates
-yrev.awk: returns -1 if option yrev is found 1 if not
-zdef.awk: returns z coordinates
-zrev.awk: returns -1 if option zrev is found 1 if not
-tdef.awk: returns number of records, units, and increment
**scripts to read variables meta information:
-varnames.awk: returns variable names
-varlevs.awk: returns the number of levels for each variable
-vardescs.awk: returns the description (long name) for each variable
-varid.awk: returns the place of a give variable name in all variables
*ncl utility script
**grads.ncl
Install .awk and .ncl scripts to appropriate directory.
Here it is assumed that they are installed in:
$HOME/lib/ncarg/nclscripts/grads/
To use this script first load this script before "begin" statement.
load "$HOME/lib/ncarg/nclscripts/grads/grads.ncl"
To read meta data use grads_addfile() function.
It simply returns the name of the input but with meta data
such as coordinates as attributes.
f = grads_addfile("path/to/your/control/file.ctl")
Available attributes are:
-grd: path to the data file ("DSET")
-title: "TITLE"
-undef: "UNDEF"
-lon: x coorinates
-lat: y coorinates
-lev: z coorinates
-varnames: names of variables
-varlevs: the number of levels for each variable
-vardescs: description (long name) of each variable
-offsets: offset of each variable from the start of the record
-nlevs: total number of levels per record
Function grads_read() returns a 2D or 3D array at a record:
x = grads_read(f,f@varnames(0),0)
Function grads_time() returns an array of increments from the initial time
with units as attributes
*Limitations
Parsing is not perfect so there are a numbers of limitations in particular:
-Byte reversing is not supported.
-mixed case such as Xdef, xDef are not supported (xdef, XDEF are OK)