DOC: Add example using high/low identification

examples/calculations/High_Low_Analysis.py

@@ -0,0 +1,64 @@
+# Copyright (c) 2025 MetPy Developers.
+# Distributed under the terms of the BSD 3-Clause License.
+# SPDX-License-Identifier: BSD-3-Clause
+"""
+=================
+High/Low Analysis
+=================
+
+This uses MetPy's `find_peaks` function to automatically identify locations of high and low
+centers, and then plots them on a map.
+"""
+
+import cartopy.crs as ccrs
+import cartopy.feature as cfeature
+import matplotlib.pyplot as plt
+import xarray as xr
+
+from metpy.calc import find_peaks
+from metpy.cbook import get_test_data
+from metpy.plots import add_metpy_logo, scattertext
+from metpy.units import units
+
+###########################################
+# Start by loading some data from our sample GFS model dataset. Pull out the geopotential
+# heights field for the 850 hPa layer, as well as grab the projection metadata.
+data = xr.open_dataset(get_test_data('GFS_test.nc', as_file_obj=False)).metpy.parse_cf()
+mslp = data.Geopotential_height_isobaric.metpy.sel(vertical=850 * units.hPa).squeeze()
+dataproj = mslp.metpy.cartopy_crs
+
+
+###########################################
+# Here we use `find_peaks` to find the locations of the highs and then the lows
+h_y, h_x = find_peaks(mslp.values)
+l_y, l_x = find_peaks(mslp.values, maxima=False)
+
+###########################################
+# Plot the analyzed locations on top of the contours of height on a map
+fig = plt.figure(figsize=(11., 8.))
+ax = fig.add_subplot(1, 1, 1, projection=ccrs.LambertConformal(central_longitude=-95))
+ax.contour(mslp.metpy.x, mslp.metpy.y, mslp, range(0, 2000, 30),
+           colors='k', linewidths=1.25, linestyles='solid', transform=dataproj)
+
+# Using scattertext() plot the high centers using a red 'H' and put the height value
+# below the 'H' using a smaller font.
+scattertext(ax, mslp.metpy.x[h_x], mslp.metpy.y[h_y], 'H', size=20, color='red',
+                    fontweight='bold', transform=dataproj)
+scattertext(ax, mslp.metpy.x[h_x], mslp.metpy.y[h_y], mslp.values[h_y, h_x],
+                    formatter='.0f', size=12, color='red', loc=(0, -15),
+                    fontweight='bold', transform=dataproj)
+
+# Now do the same for the lows using a blue 'L'
+scattertext(ax, mslp.metpy.x[l_x], mslp.metpy.y[l_y], 'L', size=20, color='blue',
+                    fontweight='bold', transform=dataproj)
+scattertext(ax, mslp.metpy.x[l_x], mslp.metpy.y[l_y], mslp.values[l_y, l_x],
+                    formatter='.0f', size=12, color='blue', loc=(0, -15),
+                    fontweight='bold', transform=dataproj)
+
+ax.add_feature(cfeature.OCEAN)
+ax.add_feature(cfeature.LAND)
+ax.add_feature(cfeature.COASTLINE)
+
+ax.set_title('Automated 850hPa High and Low Locations')
+add_metpy_logo(fig, 275, 295, size='large')
+plt.show()