Fix the spacing parameter and check required parameters in xyz2grd (#1804)

* Fix the spacing parameter and check required parameters in xyz2grd
* Add a test

Author: seisman

pygmt/src/xyz2grd.py

@@ -2,6 +2,7 @@
 xyz2grd - Convert data table to a grid.
 """
 from pygmt.clib import Session
+from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import (
     GMTTempFile,
     build_arg_string,
@@ -30,7 +31,7 @@
     r="registration",
     w="wrap",
 )
-@kwargs_to_strings(R="sequence")
+@kwargs_to_strings(I="sequence", R="sequence")
 def xyz2grd(data=None, x=None, y=None, z=None, **kwargs):
     r"""
     Create a grid file from table data.
@@ -132,6 +133,9 @@ def xyz2grd(data=None, x=None, y=None, z=None, **kwargs):
         - None if ``outgrid`` is set (grid output will be stored in file set by
           ``outgrid``)
     """
+    if "I" not in kwargs or "R" not in kwargs:
+        raise GMTInvalidInput("Both 'region' and 'spacing' must be specified.")
+
     with GMTTempFile(suffix=".nc") as tmpfile:
         with Session() as lib:
             file_context = lib.virtualfile_from_data(

pygmt/tests/test_xyz2grd.py

@@ -8,6 +8,7 @@
 import xarray as xr
 from pygmt import load_dataarray, xyz2grd
 from pygmt.datasets import load_sample_data
+from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import GMTTempFile
 
 
@@ -65,3 +66,15 @@ def test_xyz2grd_input_array_file_out(ship_data, expected_grid):
         assert os.path.exists(path=tmpfile.name)
         temp_grid = load_dataarray(tmpfile.name)
         xr.testing.assert_allclose(a=temp_grid, b=expected_grid)
+
+
+def test_xyz2grd_missing_region_spacing(ship_data):
+    """
+    Test xyz2grd raise an exception if region or spacing is missing.
+    """
+    with pytest.raises(GMTInvalidInput):
+        xyz2grd(data=ship_data)
+    with pytest.raises(GMTInvalidInput):
+        xyz2grd(data=ship_data, region=[245, 255, 20, 30])
+    with pytest.raises(GMTInvalidInput):
+        xyz2grd(data=ship_data, spacing=5)