Handle PROJ4 strings with spaces

Instead of converting spaces to \040 in proj4 strings, just remove them directly. Added parametrized unit tests to basemap and grdproject to check that it works.

Author: weiji14

pygmt/helpers/utils.py

@@ -131,6 +131,11 @@ def build_arg_string(kwargs):
     same command line argument. For example, the kwargs entry ``'B': ['xa',
     'yaf']`` will be converted to ``-Bxa -Byaf`` in the argument string.
 
+    Note that spaces ` ` in arguments are converted to the equivalent octal
+    code `\040`, except in the case of -J (projection) arguments where PROJ4
+    strings (e.g. "+proj=longlat +datum=WGS84") will have their spaces removed.
+    See https://github.com/GenericMappingTools/pygmt/pull/1487 for more info.
+
     Parameters
     ----------
     kwargs : dict
@@ -151,7 +156,7 @@ def build_arg_string(kwargs):
     ...             A=True,
     ...             B=False,
     ...             E=200,
-    ...             J="X4c",
+    ...             J="+proj=longlat +datum=WGS84",
     ...             P="",
     ...             R="1/2/3/4",
     ...             X=None,
@@ -160,7 +165,7 @@ def build_arg_string(kwargs):
     ...         )
     ...     )
     ... )
-    -A -E200 -JX4c -P -R1/2/3/4 -Z0
+    -A -E200 -J+proj=longlat+datum=WGS84 -P -R1/2/3/4 -Z0
     >>> print(
     ...     build_arg_string(
     ...         dict(
@@ -196,7 +201,12 @@ def build_arg_string(kwargs):
         elif kwargs[key] is True:
             gmt_args.append(f"-{key}")
         else:
-            _value = str(kwargs[key]).replace(" ", r"\040")
+            if key != "J":  # non-projection parameters
+                _value = str(kwargs[key]).replace(" ", r"\040")
+            else:
+                # special handling if key == "J" (projection)
+                # remove any spaces in PROJ4 string
+                _value = str(kwargs[key]).replace(" ", "")
             gmt_args.append(rf"-{key}{_value}")
     return " ".join(sorted(gmt_args))
 

pygmt/tests/baseline/test_basemap_utm_projection.png.dvc

@@ -0,0 +1,4 @@
+outs:
+- md5: e6984efed2a94673754cc7f1f1d74832
+  size: 9069
+  path: test_basemap_utm_projection.png

pygmt/tests/test_basemap.py

@@ -73,6 +73,26 @@ def test_basemap_winkel_tripel():
     return fig
 
 
+@pytest.mark.mpl_image_compare(filename="test_basemap_utm_projection.png")
+@pytest.mark.parametrize(
+    "projection",
+    [
+        "EPSG:32723 +width=5",
+        "+proj=utm +zone=23 +south +datum=WGS84 +units=m +no_defs +width=5",
+    ],
+)
+def test_basemap_utm_projection(projection):
+    """
+    Create a Universal Transverse Mercator (Zone 23S) basemap plot.
+
+    Also check that providing the projection as an EPSG code or PROJ4 string
+    works.
+    """
+    fig = Figure()
+    fig.basemap(region=[-52, -50, -12, -11], projection=projection, frame="afg")
+    return fig
+
+
 @pytest.mark.mpl_image_compare
 def test_basemap_rose():
     """

pygmt/tests/test_grdproject.py

@@ -58,13 +58,20 @@ def test_grdproject_file_out(grid, expected_grid):
         xr.testing.assert_allclose(a=temp_grid, b=expected_grid)
 
 
-def test_grdproject_no_outgrid(grid, expected_grid):
+@pytest.mark.parametrize(
+    "projection",
+    ["M10c", "EPSG:3395 +width=10", "+proj=merc +ellps=WGS84 +units=m +width=10"],
+)
+def test_grdproject_no_outgrid(grid, projection, expected_grid):
     """
     Test grdproject with no set outgrid.
+
+    Also check that providing the projection as an EPSG code or PROJ4 string
+    works.
     """
     assert grid.gmt.gtype == 1  # Geographic grid
     result = grdproject(
-        grid=grid, projection="M10c", spacing=3, region=[-53, -51, -20, -17]
+        grid=grid, projection=projection, spacing=3, region=[-53, -51, -20, -17]
     )
     assert result.gmt.gtype == 0  # Rectangular grid
     assert result.gmt.registration == 1  # Pixel registration