gridit v3.2.3¶

Mercurial revision 5770:c90c3015e72d | 2026-05-22

Description¶

gridit is a tool that converts unstructured data to structured grids. It processes input files (e.g., finite element or mesh-based data) and generates structured output in various formats such as ASCII, NetCDF, or BMG.

Usage¶

gridit input [OPTIONS] file

Options¶

Option	Description
`-h`, `--help`	Display help and exit.
`--mapping`	Define grid mapping using the format `[lonmin:dlon:lonmax; latmin:dlat:latmax]`. `dlon` and `dlat` are optional. Supported units: `d` (degrees), `m` (minutes), `'` (arcminutes), `s` (seconds), `"` (arcseconds)
`--persistence`	Number of iterations for growing unmasked pixels.
`-discretisation`	Discretization pair for NetCDF input atlas.
`-c`	NetCDF input atlas file name convention. See Notes for details.
`-g`	Grid file followed by an empty-terminated list of up to 3 gridded variable names for `e`, `u`, and `v`.
`-n`	Notebook file containing grid or projection definitions.
`-m`	Mesh file (required).
`-z`	Zone name or global resolution.
`-o`	Output root name. Default: `generic`.
`-f`	Input format. Default: `ascii`. If set to `netcdf`, discretization is compulsory.

Examples¶

Basic Conversion (ASCII Output)¶

Convert an unstructured .s2r file to ASCII format:

gridit input.s2r -f ascii -m mesh_file.nc

Convert to NetCDF with Custom Output Name¶

Convert an unstructured .s2r file to NetCDF format with a custom output name:

gridit input.s2r -f netcdf -o output_root -m mesh_file.nc

Specify Grid Span and Resolution¶

Convert an input file with a custom grid span and resolution:

gridit input.s2r -xmin 0 -xmax 10 -ymin 0 -ymax 10 -dx 0.1 -dy 0.1 -m mesh_file.nc

Use a Predefined Zone¶

Convert an input file using a predefined zone:

gridit input.s2r -z "global_1deg" -m mesh_file.nc

Apply Persistence for Unmasked Pixels¶

Convert an input file with persistence applied to unmasked pixels:

gridit input.s2r --persistence 5 -m mesh_file.nc

Custom Mapping¶

Convert an input file with a custom mapping:

gridit input.s2r --mapping "[0:0.5:10; 0:0.5:10]" -m mesh_file.nc

Convert Vector Data (V2R to NetCDF)¶

Convert a vector .v2r file to NetCDF format:

gridit input.v2r -f netcdf -m mesh_file.nc -g grid_file.nc u v

Use a Notebook File¶

Convert an input file using a notebook file for grid definitions:

gridit input.s2r -n notebook_file.txt -m mesh_file.nc

Environment Variables¶

gridit does not explicitly rely on environment variables for its core functionality. However, if used in conjunction with other tools or scripts, standard environment variables (e.g., PATH, LD_LIBRARY_PATH) may apply.

Notes¶

Input Files:

Supported input formats: .s2r, .s2c, .v2r, .v2c.
The -m (mesh file) option is required for all conversions.

Output Formats:

Supported output formats: ascii, netcdf, grd, bmg.
If the output format is netcdf, the -discretisation option may be required for proper handling of the input atlas.

Grid and Mesh:

The -g option requires a grid file followed by up to 3 variable names (e.g., for e, u, and v components in vector data).
The --mapping option allows flexible grid definitions. Ensure the syntax is correct (e.g., [lonmin:dlon:lonmax; latmin:dlat:latmax]).

Resolution Units:

Units for -dx and -dy can be specified as:
- d: Degrees
- m: Minutes
- ' : Arcminutes
- s: Seconds
- ": Arcseconds
Example: -dx 30' (30 arcminutes) or -dy 0.5d (0.5 degrees).

Persistence:

The --persistence option is useful for filling gaps in unmasked regions by iteratively growing unmasked pixels.

Zone and Global Resolution:

The -z option can specify a predefined zone (e.g., global_1deg) or a global resolution.