DOC: Simplify the Cross Section gallery example using Figure.fill_between

examples/gallery/images/cross_section.py

@@ -17,15 +17,13 @@
 from pygmt.params import Axis, Box, Frame, Position
 
 # Define region of study area
-# lon_min, lon_max, lat_min, lat_max in degrees East and North
 region_map = [122, 149, 30, 49]
 
 # Chose a survey line with start point A and end point B
 lonA, latA, lonB, latB = 126, 42, 146, 40  # noqa: N816
 
-# Create a new pygmt.Figure instance
-fig = pygmt.Figure()
 
+fig = pygmt.Figure()
 # ----------------------------------------------------------------------------
 # Bottom: Map of elevation in study area
 
@@ -71,12 +69,8 @@
 # Shift plot origin to the top by the height of the map ("+h") plus 1.5 centimeters
 fig.shift_origin(yshift="h+1.5c")
 
-fig.basemap(
-    region=[0, 15, -8000, 6000],  # xmin, xmax, ymin, ymax
-    # Cartesian projection with a width of 12 centimeters and a height of 3 centimeters
-    projection="X12c/3c",
-    frame=0,
-)
+# Cartesian projection with a width of 12 centimeters and a height of 3 centimeters
+fig.basemap(region=[0, 15, -8000, 6000], projection="X12c/3c", frame=0)
 
 # Add labels "A" and "B" for the start and end points of the survey line
 fig.text(
@@ -99,22 +93,12 @@
 # new column "elevation" to the pandas.DataFrame
 track_df = pygmt.grdtrack(grid=grid_map, points=track_df, newcolname="elevation")
 
-# Plot water masses
-fig.plot(
-    x=[0, 15],
-    y=[0, 0],
-    fill="lightblue",  # Fill the polygon in "lightblue"
-    pen="0.25p,black,solid",  # Draw a 0.25-point thick, black, solid outline
-    close="+y-8000",  # Force closed polygon
-)
+# Plot water masses down to -8000 meters below sea level as a light blue area.
+fig.fill_between(x=[0, 15], y=[0, 0], y2=-8000, pen="0.25p", fill="lightblue")
 
-# Plot elevation along the survey line
-fig.plot(
-    x=track_df.p,
-    y=track_df.elevation,
-    fill="gray",
-    pen="1p,red,solid",
-    close="+y-8000",
+# Plot elevation along the survey line, filled down to -8000 meters below sea level.
+fig.fill_between(
+    x=track_df.p, y=track_df.elevation, y2=-8000, pen="1p,red", fill="gray"
 )
 
 # Add map frame