Add HRRR ptype reflectivity helpers.

.pre-commit-config.yaml

@@ -2,7 +2,7 @@ ci:
   autoupdate_schedule: quarterly
 repos:
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: "v0.6.5"
+    rev: "v0.6.7"
     hooks:
       - id: ruff
         args: [--fix, --exit-non-zero-on-fix]

CHANGELOG.md

@@ -11,6 +11,8 @@ All notable changes to this library are documented in this file.
 
 - Add `allowed_as_list` option to `iemapp()` helper to stop lists.
 - Add support for plotting by FEMA Regions.
+- Introduce `radar_ptype` color ramp and `draw_radar_ptype_legend` for
+generating plots of HRRR ptype.
 
 ### Bug Fixes
 

src/pyiem/plot/colormaps.py

@@ -174,3 +174,35 @@ def maue():
     cmap3 = mpcolors.ListedColormap(cpool, "maue")
     _register_cmap(cmap=cmap3)
     return cmap3
+
+
+def radar_ptype() -> dict[str, list]:
+    """Generate a dictionary of colors for HRRR Ptype."""
+    return {
+        "rain": (
+            # 0-40 by 2.5, Green
+            "#eef8ea #e5f5e0 #d6efd0 #c7e9c0 #b4e1ad #a0d99b #8ace88 #73c476 "
+            "#5ab769 #40aa5d #319a50 #228a44 #117b38 #006c2c #005723 #00441b "
+            # 40-55 by 2.5, Wistia
+            "#ffe81a #ffd710 #ffc505 #ffb700 #ffab00 #ffa000"
+        ).split(),
+        "snow": (
+            # 0-40 by 2.5, 16 colors from ocean_r
+            "#b4dae6 #99ccdd #81c0d5 #66b3cc #4ea6c4 #3399bb #1b8db3 #0080aa "
+            "#0073a2 #006699 #005a91 #004d88 #003f7f #003377 #00266e #001a66 "
+            # 40-55 by 2.5, 6 colors from PuRd_r
+            "#8d003b #b80b4e #d81b6a #e53592 #df66b0 #cd8bc2"
+        ).split(),
+        "frzr": (
+            # 0-55 by 2.5, 22 colors Reds
+            "#ffeee6 #fee6da #fedecf #fdd0bc #fcc2aa #fcb499 #fca588 #fc9576 "
+            "#fc8767 #fb7858 #fb694a #f7593f #f24734 #ec382b #de2b25 #d11e1f "
+            "#c4161c #b61319 #a81016 #940b13 #7c0510 #67000d"
+        ).split(),
+        "icep": (
+            # 0-55 by 2.5, 22 colors Purples
+            "#f8f6fa #f3f1f7 #eeecf4 #e6e5f1 #dedded #d5d5e9 #cacae3 #bebfdd "
+            "#b4b4d7 #a9a7cf #9e9ac8 #9390c3 #8885be #7e79b8 #7669af #6e58a7 "
+            "#66499f #5e3a98 #552a90 #4e1c8a #460d83 #3f007d"
+        ).split(),
+    }

src/pyiem/plot/geoplot.py

@@ -46,7 +46,7 @@
 from scipy.signal import convolve2d
 from shapely.geometry import shape
 
-from pyiem.plot.colormaps import stretch_cmap
+from pyiem.plot.colormaps import radar_ptype, stretch_cmap
 
 # local
 from pyiem.plot.use_agg import plt
@@ -409,6 +409,47 @@ def draw_usdm(self, valid=None, filled=True, hatched=False, **kwargs):
             return datetime.datetime.strptime(usdm_valid, "%Y-%m-%d")
         return None
 
+    def draw_radar_ptype_legend(self):
+        """Draw a legend for radar precipitation type."""
+        ramps = radar_ptype()
+        pos = self.cax.get_position()
+        w75 = pos.width * 0.75
+        x0 = pos.x0 + 0.015
+        axes = [
+            self.fig.add_axes((x0, pos.y0, w75, pos.height / 5)),
+            self.fig.add_axes(
+                (x0, pos.y0 + pos.height / 4, w75, pos.height / 5)
+            ),
+            self.fig.add_axes(
+                (x0, pos.y0 + pos.height / 2, w75, pos.height / 5)
+            ),
+            self.fig.add_axes(
+                (x0, pos.y0 + pos.height * 0.75, w75, pos.height / 5)
+            ),
+        ]
+        levels = np.arange(0, 55.1, 2.5)
+        norm = mpcolors.BoundaryNorm(levels, 22)
+        for i, (name, colors) in enumerate(ramps.items()):
+            cmap = mpcolors.ListedColormap(colors, name=name)
+            cb = plt.colorbar(
+                mpcm.ScalarMappable(norm=norm, cmap=cmap),
+                cax=axes[i],
+                boundaries=levels,
+                ticks=range(0, 51, 10),
+                spacing="uniform",
+                orientation="vertical",
+            )
+            # Remove minor ticks
+            cb.ax.yaxis.set_tick_params(which="minor", width=0)
+            cb.ax.text(
+                -0.03,
+                0.5,
+                name if name != "icep" else "sleet",
+                va="center",
+                ha="right",
+                rotation=90,
+            )
+
     def draw_colorbar(self, clevs, cmap, norm, **kwargs):
         """Draw the colorbar on the structed plot using `self.cax`.
 

tests/plot/test_geoplot.py

@@ -52,6 +52,14 @@ def test_invalid_file():
     assert load_bounds("this shall not work") is None
 
 
+@pytest.mark.mpl_image_compare(tolerance=PAIN)
+def test_radar_ptype_legend():
+    """Test the plotting of the ptype reflectivity legend."""
+    mp = MapPlot(nocaption=True, sector="iowa")
+    mp.draw_radar_ptype_legend()
+    return mp.fig
+
+
 @pytest.mark.mpl_image_compare(tolerance=PAIN)
 def test_nws_with_axes_position_set():
     """Test that the inset axes work out."""