Source code for pygmt.src.grdcut

grdcut - Extract subregion from a grid.

from pygmt.clib import Session
from pygmt.helpers import (
from import load_dataarray

__doctest_skip__ = ["grdcut"]

[docs] @fmt_docstring @use_alias( G="outgrid", R="region", J="projection", N="extend", S="circ_subregion", V="verbose", Z="z_subregion", f="coltypes", ) @kwargs_to_strings(R="sequence") def grdcut(grid, **kwargs): r""" Extract subregion from a grid. Produce a new ``outgrid`` file which is a subregion of ``grid``. The subregion is specified with ``region``; the specified range must not exceed the range of ``grid`` (but see ``extend``). If in doubt, run :func:`pygmt.grdinfo` to check range. Alternatively, define the subregion indirectly via a range check on the node values or via distances from a given point. Finally, you can give ``projection`` for oblique projections to determine the corresponding rectangular ``region`` that will give a grid that fully covers the oblique domain. Full option list at :gmt-docs:`grdcut.html` {aliases} Parameters ---------- {grid} {outgrid} {projection} {region} extend : bool or float Allow grid to be extended if new ``region`` exceeds existing boundaries. Give a value to initialize nodes outside current region. circ_subregion : str *lon/lat/radius*\[\ *unit*\][**+n**]. Specify an origin (*lon* and *lat*) and *radius*; append a distance *unit* and we determine the corresponding rectangular region so that all grid nodes on or inside the circle are contained in the subset. If **+n** is appended we set all nodes outside the circle to NaN. z_subregion : str [*min/max*\][**+n**\|\ **N**\|\ **r**]. Determine a new rectangular region so that all nodes outside this region are also outside the given z-range [-inf/+inf]. To indicate no limit on *min* or *max* only, specify a hyphen (-). Normally, any NaNs encountered are simply skipped and not considered in the range-decision. Append **+n** to consider a NaN to be outside the given z-range. This means the new subset will be NaN-free. Alternatively, append **+r** to consider NaNs to be within the data range. In this case we stop shrinking the boundaries once a NaN is found [Default simply skips NaNs when making the range decision]. Finally, if your core subset grid is surrounded by rows and/or columns that are all NaNs, append **+N** to strip off such columns before (optionally) considering the range of the core subset for further reduction of the area. {verbose} {coltypes} 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 >>> # Load a grid of @earth_relief_30m data, with a longitude range of >>> # 10° E to 30° E, and a latitude range of 15° N to 25° N >>> grid = pygmt.datasets.load_earth_relief( ... resolution="30m", region=[10, 30, 15, 25] ... ) >>> # Create a new grid from an input grid, with a longitude range of >>> # 12° E to 15° E and a latitude range of 21° N to 24° N >>> new_grid = pygmt.grdcut(grid=grid, region=[12, 15, 21, 24]) """ with GMTTempFile(suffix=".nc") as tmpfile: with Session() as lib: with lib.virtualfile_in(check_kind="raster", data=grid) as vingrd: if (outgrid := kwargs.get("G")) is None: kwargs["G"] = outgrid = # output to tmpfile lib.call_module( module="grdcut", args=build_arg_list(kwargs, infile=vingrd) ) return load_dataarray(outgrid) if outgrid == else None