Add earth_relief_holes to load_sample_data() (#1921)

Co-authored-by: Wei Ji <23487320+weiji14@users.noreply.github.com>
Co-authored-by: Dongdong Tian <seisman.info@gmail.com>

pygmt/datasets/samples.py

@@ -5,6 +5,7 @@
 
 import pandas as pd
 from pygmt.exceptions import GMTInvalidInput
+from pygmt.io import load_dataarray
 from pygmt.src import which
 
 
@@ -23,6 +24,7 @@ def list_sample_data():
     """
     names = {
         "bathymetry": "Table of ship bathymetric observations off Baja California",
+        "earth_relief_holes": "Regional 20 arc-minute Earth relief grid with holes",
         "fractures": "Table of hypothetical fracture lengths and azimuths",
         "hotspots": "Table of locations, names, and symbol sizes of hotpots from "
         " Mueller et al., 1993",
@@ -65,6 +67,7 @@ def load_sample_data(name):
 
     load_func = {
         "bathymetry": load_sample_bathymetry,
+        "earth_relief_holes": _load_earth_relief_holes,
         "fractures": load_fractures_compilation,
         "hotspots": load_hotspots,
         "japan_quakes": load_japan_quakes,
@@ -343,3 +346,17 @@ def load_mars_shape(**kwargs):
         fname, sep="\t", header=None, names=["longitude", "latitude", "radius(m)"]
     )
     return data
+
+
+def _load_earth_relief_holes(**kwargs):  # pylint: disable=unused-argument
+    """
+    Loads the remote file @earth_relief_20m_holes.grd.
+
+    Returns
+    -------
+    grid : :class:`xarray.DataArray`
+        The Earth relief grid. Coordinates are latitude and longitude in
+        degrees. Relief is in meters.
+    """
+    fname = which("@earth_relief_20m_holes.grd", download="c")
+    return load_dataarray(fname, engine="netcdf4")

pygmt/helpers/testing.py

@@ -171,6 +171,7 @@ def download_test_data():
         "@earth_age_01d_g",
         "@S90W180.earth_age_05m_g.nc",  # Specific grid for 05m test
         # Other cache files
+        "@earth_relief_20m_holes.grd",
         "@EGM96_to_36.txt",
         "@MaunaLoa_CO2.txt",
         "@RidgeTest.shp",

pygmt/tests/test_datasets_samples.py

@@ -1,6 +1,7 @@
 """
 Test basic functionality for loading sample datasets.
 """
+import numpy.testing as npt
 import pandas as pd
 import pytest
 from pygmt.datasets import (
@@ -145,3 +146,15 @@ def test_hotspots():
         "place_name",
     ]
     assert isinstance(data, pd.DataFrame)
+
+
+def test_earth_relief_holes():
+    """
+    Check that the @earth_relief_20m_holes.grd dataset loads without errors.
+    """
+    grid = load_sample_data(name="earth_relief_holes")
+    assert grid.shape == (31, 31)
+    npt.assert_allclose(grid.max(), 1601)
+    npt.assert_allclose(grid.min(), -4929.5)
+    # Test for the NaN values in the remote file
+    assert grid[2, 21].isnull()