load_earth_relief() now returns gridline-registrated grids by default in GMT 6.4 (#2052)

* pygmt.datasets.load_earth_relief() now returns gridline-registrated grids by default in GMT 6.4
* Add a note for GMT 6.3

Author: seisman

pygmt/accessors.py

@@ -15,7 +15,7 @@ class GMTDataArrayAccessor:
 
     >>> from pygmt.datasets import load_earth_relief
     >>> # Use the global Earth relief grid with 1 degree spacing
-    >>> grid = load_earth_relief(resolution="01d")
+    >>> grid = load_earth_relief(resolution="01d", registration="pixel")
 
     >>> # See if grid uses Gridline (0) or Pixel (1) registration
     >>> grid.gmt.registration

pygmt/clib/conversion.py

@@ -48,7 +48,7 @@ def dataarray_to_matrix(grid):
 
     >>> from pygmt.datasets import load_earth_relief
     >>> # Use the global Earth relief grid with 1 degree spacing
-    >>> grid = load_earth_relief(resolution="01d")
+    >>> grid = load_earth_relief(resolution="01d", registration="pixel")
     >>> matrix, region, inc = dataarray_to_matrix(grid)
     >>> print(region)
     [-180.0, 180.0, -90.0, 90.0]

pygmt/datasets/earth_relief.py

@@ -46,13 +46,16 @@ def load_earth_relief(resolution="01d", region=None, registration=None, use_srtm
     registration : str
         Grid registration type. Either ``pixel`` for pixel registration or
         ``gridline`` for gridline registration. Default is ``None``, where
-        a pixel-registered grid is returned unless only the
-        gridline-registered grid is available.
+        a gridline-registered grid is returned unless only the pixel-registered
+        grid is available.
+
+        **Note:** For GMT 6.3, ``registration=None`` returns a pixel-registered
+        grid by default unless only the gridline-registered grid is available.
 
     use_srtm : bool
         By default, the land-only SRTM tiles from NASA are used to generate the
         ``'03s'`` and ``'01s'`` grids, and the missing ocean values are filled
-        by up-sampling the SRTM15+V2.1 tiles which have a resolution of 15
+        by up-sampling the SRTM15+ tiles which have a resolution of 15
         arc-second (i.e., ``'15s'``). If True, will only load the original
         land-only SRTM tiles.
 
@@ -71,7 +74,7 @@ def load_earth_relief(resolution="01d", region=None, registration=None, use_srtm
     Examples
     --------
 
-    >>> # load the default grid (pixel-registered 01d grid)
+    >>> # load the default grid (gridline-registered 01d grid)
     >>> grid = load_earth_relief()
     >>> # load the 30m grid with "gridline" registration
     >>> grid = load_earth_relief("30m", registration="gridline")