Figure.savefig: Support generating GeoTIFF file (with extension '.tiff')

pygmt/figure.py

@@ -257,12 +257,19 @@ def savefig(
         """
         Save the figure to a file.
 
-        This method implements a matplotlib-like interface for
-        :meth:`pygmt.Figure.psconvert`.
+        Supported file formats and their extensions:
 
-        Supported formats: PNG (``.png``), JPEG (``.jpg`` or ``.jpeg``),
-        PDF (``.pdf``), BMP (``.bmp``), TIFF (``.tif``), EPS (``.eps``), and
-        KML (``.kml``). The KML output generates a companion PNG file.
+        - PNG (``.png``)
+        - JPEG (``.jpg`` or ``.jpeg``)
+        - PDF (``.pdf``)
+        - BMP (``.bmp``)
+        - TIFF (``.tif`` or ``.tiff``)
+        - EPS (``.eps``)
+        - KML (``.kml``)
+
+        For TIFF format, ``.tiff`` generates a GeoTIFF file with embedded
+        georeferencing information and a companion world file. For KML format,
+        a companion PNG file is also generated.
 
         You can pass in any keyword arguments that
         :meth:`pygmt.Figure.psconvert` accepts.
@@ -279,10 +286,10 @@ def savefig(
             If ``True``, will crop the figure canvas (page) to the plot area.
         anti_alias: bool
             If ``True``, will use anti-aliasing when creating raster images
-            (PNG, JPG, TIFF). More specifically, it passes arguments ``t2``
-            and ``g2`` to the ``anti_aliasing`` parameter of
-            :meth:`pygmt.Figure.psconvert`. Ignored if creating vector
-            graphics.
+            (BMP, PNG, JPEG, and TIFF). More specifically, it passes the
+            arguments ``"t2"`` and ``"g2"`` to the ``anti_aliasing``
+            parameter of :meth:`pygmt.Figure.psconvert`. Ignored if
+            creating vector graphics.
         show: bool
             If ``True``, will open the figure in an external viewer.
         dpi : int
@@ -301,15 +308,20 @@ def savefig(
             "bmp": "b",
             "eps": "e",
             "tif": "t",
+            "tiff": None,  # GeoTIFF doesn't need the -T option
             "kml": "g",
         }
 
         fname = Path(fname)
         prefix, suffix = fname.with_suffix("").as_posix(), fname.suffix
         ext = suffix[1:].lower()  # Remove the . and normalize to lowercase
-        # alias jpeg to jpg
-        if ext == "jpeg":
+
+        if ext == "jpeg":  # Alias jpeg to jpg
             ext = "jpg"
+        elif ext == "tiff":  # GeoTIFF
+            kwargs["W"] = "+g"
+        elif ext == "kml":  # KML
+            kwargs["W"] = "+k"
 
         if ext not in fmts:
             if ext == "ps":
@@ -328,8 +340,6 @@ def savefig(
         if anti_alias:
             kwargs["Qt"] = 2
             kwargs["Qg"] = 2
-        if ext == "kml":
-            kwargs["W"] = "+k"
 
         self.psconvert(prefix=prefix, fmt=fmt, crop=crop, **kwargs)
 

pygmt/tests/test_figure.py

@@ -92,6 +92,46 @@ def test_figure_savefig_exists():
         fname.unlink()
 
 
+def test_figure_savefig_geotiff():
+    """
+    Make sure .tif generates a normal TIFF file and .tiff generates a GeoTIFF
+    file.
+    """
+    fig = Figure()
+    fig.basemap(region=[0, 10, 0, 10], projection="M10c", frame=True)
+
+    # Save as GeoTIFF
+    geofname = Path("test_figure_savefig_geotiff.tiff")
+    fig.savefig(geofname)
+    assert geofname.exists()
+    assert geofname.with_suffix(".pgw").exists()  # The companion world file
+
+    # Save as TIFF
+    fname = Path("test_figure_savefig_geotiff.tif")
+    fig.savefig(fname)
+    assert fname.exists()
+
+    # Check if a TIFF is georeferenced or not
+    try:
+        # pylint: disable=import-outside-toplevel
+        import rioxarray
+        from rasterio.errors import NotGeoreferencedWarning
+
+        # GeoTIFF
+        with rioxarray.open_rasterio(geofname) as xds:
+            assert xds.rio.crs is not None
+        # TIFF
+        with pytest.warns(expected_warning=NotGeoreferencedWarning) as record:
+            with rioxarray.open_rasterio(fname) as xds:
+                assert xds.rio.crs is None
+            assert len(record) == 1
+    except ImportError:
+        pass
+    geofname.unlink()
+    geofname.with_suffix(".pgw").unlink()
+    fname.unlink()
+
+
 def test_figure_savefig_directory_nonexists():
     """
     Make sure that Figure.savefig() raises a FileNotFoundError when the parent