"""
grdsample - Resample a grid onto a new lattice
"""
from pygmt.clib import Session
from pygmt.helpers import (
GMTTempFile,
build_arg_string,
fmt_docstring,
kwargs_to_strings,
use_alias,
)
from pygmt.io import load_dataarray
[docs]@fmt_docstring
@use_alias(
G="outgrid",
I="spacing",
R="region",
T="translate",
V="verbose",
f="coltypes",
n="interpolation",
r="registration",
x="cores",
)
@kwargs_to_strings(I="sequence", R="sequence")
def grdsample(grid, **kwargs):
r"""
Change the registration, spacing, or nodes in a grid file.
This reads a grid file and interpolates it to create a new grid
file. It can change the registration with ``translate`` or
``registration``, change the grid-spacing or number of nodes with
``spacing``, and set a new sub-region using ``region``. A bicubic
[Default], bilinear, B-spline or nearest-neighbor interpolation is set
with ``interpolation``.
When ``region`` is omitted, the output grid will cover the same region as
the input grid. When ``spacing`` is omitted, the grid spacing of the
output grid will be the same as the input grid. Either ``registration`` or
``translate`` can be used to change the grid registration. When omitted,
the output grid will have the same registration as the input grid.
{aliases}
Parameters
----------
grid : str or xarray.DataArray
The file name of the input grid or the grid loaded as a DataArray.
outgrid : str or None
The name of the output netCDF file with extension .nc to store the grid
in.
{I}
{R}
translate : bool
Translate between grid and pixel registration; if the input is
grid-registered, the output will be pixel-registered and vice-versa.
registration : str or bool
[**g**\|\ **p**\ ].
Set registration to **g**\ ridline or **p**\ ixel.
{V}
{f}
{n}
{x}
Returns
-------
ret: xarray.DataArray or None
Return type depends on whether the ``outgrid`` parameter is set:
- :class:`xarray.DataArray` if ``outgrid`` is not set
- None if ``outgrid`` is set (grid output will be stored in file set by
``outgrid``)
Example
-------
>>> import pygmt # doctest: +SKIP
>>> # Load a grid of @earth_relief_30m data, with an x-range of 10 to 30,
>>> # and a y-range of 15 to 25
>>> grid = pygmt.datasets.load_earth_relief(
... resolution="30m", region=[10, 30, 15, 25]
... ) # doctest: +SKIP
>>> # Create a new grid from an input grid, change the registration,
>>> # and set both x- and y-spacing to 0.5 degrees
>>> new_grid = pygmt.grdsample(
... grid=grid, translate=True, spacing=[0.5, 0.5]
... ) # doctest: +SKIP
"""
with GMTTempFile(suffix=".nc") as tmpfile:
with Session() as lib:
file_context = lib.virtualfile_from_data(check_kind="raster", data=grid)
with file_context as infile:
if "G" not in kwargs: # if outgrid is unset, output to tempfile
kwargs.update({"G": tmpfile.name})
outgrid = kwargs["G"]
arg_str = " ".join([infile, build_arg_string(kwargs)])
lib.call_module("grdsample", arg_str)
return load_dataarray(outgrid) if outgrid == tmpfile.name else None