Source code for pygmt.src.grdproject

grdproject - Forward and inverse map transformation of grids.

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

[docs]@fmt_docstring @use_alias( C="center", D="spacing", E="dpi", F="scaling", G="outgrid", J="projection", I="inverse", M="unit", R="region", V="verbose", n="interpolation", r="registration", ) @kwargs_to_strings(C="sequence", R="sequence") def grdproject(grid, **kwargs): r""" Change projection of gridded data between geographical and rectangular. This module will project a geographical gridded data set onto a rectangular grid. If ``inverse`` is ``True``, it will project a rectangular coordinate system to a geographic system. To obtain the value at each new node, its location is inversely projected back onto the input grid after which a value is interpolated between the surrounding input grid values. By default bi-cubic interpolation is used. Aliasing is avoided by also forward projecting the input grid nodes. If two or more nodes are projected onto the same new node, their average will dominate in the calculation of the new node value. Interpolation and aliasing is controlled with the ``interpolation`` option. The new node spacing may be determined in one of several ways by specifying the grid spacing, number of nodes, or resolution. Nodes not constrained by input data are set to NaN. The ``region`` parameter can be used to select a map region larger or smaller than that implied by the extent of the grid file. {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. inverse : bool When set to ``True`` transforms grid from rectangular to geographical [Default is False]. {J} {R} center : str or list [*dx*, *dy*]. Let projected coordinates be relative to projection center [Default is relative to lower left corner]. Optionally, add offsets in the projected units to be added (or subtracted when ``inverse`` is set) to (from) the projected coordinates, such as false eastings and northings for particular projection zones [0/0]. {I} dpi : int Set the resolution for the new grid in dots per inch. scaling : str [**c**\|\ **i**\|\ **p**\|\ **e**\|\ **f**\|\ **k**\|\ **M**\|\ **n**\|\ **u**]. Force 1:1 scaling, i.e., output or output data are in actual projected meters [**e**]. To specify other units, append **f** (foot), **k** (km), **M** (statute mile), **n** (nautical mile), **u** (US survey foot), **i** (inch), **c** (cm), or **p** (point). unit : str Append **c**, **i**, or **p** to indicate that cm, inch, or point should be the projected measure unit. Cannot be used with ``scaling``. {V} {n} {r} 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``) """ if "J" not in kwargs.keys(): raise GMTInvalidInput("The projection must be specified.") 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.keys(): # if outgrid is unset, output to tempfile kwargs.update({"G":}) outgrid = kwargs["G"] arg_str = " ".join([infile, build_arg_string(kwargs)]) lib.call_module("grdproject", arg_str) return load_dataarray(outgrid) if outgrid == else None