Wrap grdlandmask

doc/api/index.rst

@@ -92,6 +92,7 @@ Operations on grids:
     grdcut
     grdfill
     grdfilter
+    grdlandmask
     grdtrack
 
 Crossover analysis with x2sys:

pygmt/__init__.py

@@ -38,6 +38,7 @@
     grdfill,
     grdfilter,
     grdinfo,
+    grdlandmask,
     grdtrack,
     info,
     makecpt,

pygmt/src/__init__.py

@@ -17,6 +17,7 @@
 from pygmt.src.grdfilter import grdfilter
 from pygmt.src.grdimage import grdimage
 from pygmt.src.grdinfo import grdinfo
+from pygmt.src.grdlandmask import grdlandmask
 from pygmt.src.grdtrack import grdtrack
 from pygmt.src.grdview import grdview
 from pygmt.src.histogram import histogram

pygmt/src/grdlandmask.py

@@ -0,0 +1,94 @@
+"""
+grdlandmask - Create a "wet-dry" mask grid from shoreline data base
+"""
+
+import xarray as xr
+from pygmt.clib import Session
+from pygmt.exceptions import GMTInvalidInput
+from pygmt.helpers import (
+    GMTTempFile,
+    build_arg_string,
+    fmt_docstring,
+    kwargs_to_strings,
+    use_alias,
+)
+
+
+@fmt_docstring
+@use_alias(
+    G="outgrid",
+    R="region",
+    I="increment",
+    r="registration",
+)
+@kwargs_to_strings(R="sequence")
+def grdlandmask(**kwargs):
+    r"""
+    Create a grid file with set values for land and water.
+
+    Read the selected shoreline database and create a grid to specify which
+    nodes in the specified grid are over land or over water. The nodes defined
+    by the selected region and lattice spacing
+    will be set according to one of two criteria: (1) land vs water, or
+    (2) the more detailed (hierarchical) ocean vs land vs lake
+    vs island vs pond.
+
+    Full option list at :gmt-docs:`grdlandmask.html`
+
+    {aliases}
+
+    Parameters
+    ----------
+    outgrid : str or None
+        The name of the output netCDF file with extension .nc to store the grid
+        in.
+    increment : str
+        *xinc*\ [**+e**\|\ **n**][/\ *yinc*\ [**+e**\|\ **n**]].
+        *x_inc* [and optionally *y_inc*] is the grid spacing. **Geographical
+        (degrees) coordinates**: Optionally, append a increment unit. Choose
+        among **m** to indicate arc minutes or **s** to indicate arc seconds.
+        If one of the units **e**, **f**, **k**, **M**, **n** or **u** is
+        appended instead, the increment is assumed to be given in meter, foot,
+        km, mile, nautical mile or US survey foot, respectively, and will be
+        converted to the equivalent degrees longitude at the middle latitude
+        of the region. If *y_inc* is given but set to 0 it will be reset equal
+        to *x_inc*; otherwise it will be converted to degrees latitude. **All
+        coordinates**: If **+e** is appended then the corresponding max
+        *x* (*east*) or *y* (*north*) may be slightly adjusted to fit exactly
+        the given increment [by default the increment may be adjusted slightly
+        to fit the given domain]. Finally, instead of giving an increment you
+        may specify the *number of nodes* desired by appending **+n** to the
+        supplied integer argument; the increment is then recalculated from the
+        number of nodes, the *registration*, and the domain. The resulting
+        increment value depends on whether you have selected a
+        gridline-registered or pixel-registered grid.
+    {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 "I" not in kwargs.keys() or "R" not in kwargs.keys():
+        raise GMTInvalidInput("Region and increment must be specified.")
+
+    with GMTTempFile(suffix=".nc") as tmpfile:
+        with Session() as lib:
+            if "G" not in kwargs.keys():  # if outgrid is unset, output to tempfile
+                kwargs.update({"G": tmpfile.name})
+            outgrid = kwargs["G"]
+            arg_str = build_arg_string(kwargs)
+            lib.call_module("grdlandmask", arg_str)
+
+        if outgrid == tmpfile.name:  # if user did not set outgrid, return DataArray
+            with xr.open_dataarray(outgrid) as dataarray:
+                result = dataarray.load()
+                _ = result.gmt  # load GMTDataArray accessor information
+        else:
+            result = None  # if user sets an outgrid, return None
+
+        return result

pygmt/tests/test_grdlandmask.py

@@ -0,0 +1,43 @@
+"""
+Tests for grdlandmask.
+"""
+import os
+
+import pytest
+from pygmt import grdinfo, grdlandmask
+from pygmt.exceptions import GMTInvalidInput
+from pygmt.helpers import GMTTempFile
+
+
+def test_grdlandmask_outgrid():
+    """
+    Creates a grid land mask with an outgride argument.
+    """
+    with GMTTempFile(suffix=".nc") as tmpfile:
+        result = grdlandmask(outgrid=tmpfile.name, increment=1, region=[-5, 5, -5, 5])
+        assert result is None  # return value is None
+        assert os.path.exists(path=tmpfile.name)  # check that outgrid exists
+        result = (
+            grdinfo(grid=tmpfile.name, force_scan=0, per_column="n").strip().split()
+        )
+    assert result == ["-5", "5", "-5", "5", "0", "1", "1", "1", "11", "11", "0", "1"]
+
+
+def test_grdlandmask_no_outgrid():
+    """
+    Test grdlandmask with no set outgrid.
+    """
+    temp_grid = grdlandmask(increment=1, region=[-5, 5, -5, 5])
+    assert temp_grid.dims == ("lat", "lon")
+    assert temp_grid.gmt.gtype == 1  # Geographic grid
+    assert temp_grid.gmt.registration == 0
+    assert temp_grid.min() == 0
+    assert temp_grid.max() == 1
+
+
+def test_grdlandmask_fails():
+    """
+    Check that grdlandmask fails correctly.
+    """
+    with pytest.raises(GMTInvalidInput):
+        grdlandmask()