DOC: Polish gallery example "Cross-section along a transect" (#3967)

Author: yvonnefroehlich

examples/gallery/images/cross_section.py

@@ -19,6 +19,9 @@
 # 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()
 
@@ -39,30 +42,25 @@
 fig.colorbar(
     # Place the colorbar inside the plot (lowercase "j") in the Bottom Right (BR)
     # corner with an offset ("+o") of 0.7 centimeters and 0.3 centimeters in x- or y-
-    # directions, respectively; move the x label above the horizontal colorbar ("+ml")
+    # directions, respectively; move the x-label above the horizontal colorbar ("+ml")
     position="jBR+o0.7c/0.8c+h+w5c/0.3c+ml",
     # Add a box around the colobar with a fill ("+g") in "white" color and a
     # transparency ("@") of 30 % and with a 0.8-points thick, black, outline ("+p")
     box="+gwhite@30+p0.8p,black",
-    # Add x and y labels ("+l")
+    # Add x- and y-labels ("+l")
     frame=["x+lElevation", "y+lm"],
 )
 
-# Choose a survey line
-fig.plot(
-    x=[126, 146],  # Longitude in degrees East
-    y=[42, 40],  # Latitude in degrees North
-    # Draw a 2-points thick, red, dashed line for the survey line
-    pen="2p,red,dashed",
-)
+# Plot the survey line
+fig.plot(x=[lonA, lonB], y=[latA, latB], pen="1p,red,solid")
 
 # Add labels "A" and "B" for the start and end points of the survey line
 fig.text(
-    x=[126, 146],
-    y=[42, 40],
+    x=[lonA, lonB],
+    y=[latA, latB],
     text=["A", "B"],
-    offset="0c/0.2c",  # Move text 0.2 centimeters up (y-direction)
-    font="15p",  # Use a font size of 15 points
+    offset="0c/0.3c",  # Move text 0.2 centimeters up (y-direction)
+    font="15p,red",  # Use a red font with a size of 15 points
 )
 
 # ----------------------------------------------------------------------------
@@ -75,9 +73,7 @@
     region=[0, 15, -8000, 6000],  # x_min, x_max, y_min, y_max
     # Cartesian projection with a width of 12 centimeters and a height of 3 centimeters
     projection="X12c/3c",
-    # Add annotations ("a") and ticks ("f") as well as labels ("+l") at the west or
-    # left and south or bottom sides ("WSrt")
-    frame=["WSrt", "xa2f1+lDistance+u°", "ya4000+lElevation / m"],
+    frame=0,
 )
 
 # Add labels "A" and "B" for the start and end points of the survey line
@@ -86,14 +82,14 @@
     y=[7000, 7000],
     text=["A", "B"],
     no_clip=True,  # Do not clip text that fall outside the plot bounds
-    font="10p",  # Use a font size of 10 points
+    font="10p,red",
 )
 
 # Generate points along a great circle corresponding to the survey line and store them
 # in a pandas.DataFrame
 track_df = pygmt.project(
-    center=[126, 42],  # Start point of survey line (longitude, latitude)
-    endpoint=[146, 40],  # End point of survey line (longitude, latitude)
+    center=[lonA, latA],  # Start point of survey line (longitude, latitude)
+    endpoint=[lonB, latB],  # End point of survey line (longitude, latitude)
     generate=0.1,  # Output data in steps of 0.1 degrees
 )
 
@@ -106,19 +102,22 @@
     x=[0, 15],
     y=[0, 0],
     fill="lightblue",  # Fill the polygon in "lightblue"
-    # Draw a 0.25-points thick, black, solid outline
-    pen="0.25p,black,solid",
+    pen="0.25p,black,solid",  # Draw a 0.25-points thick, black, solid outline
     close="+y-8000",  # Force closed polygon
 )
 
 # Plot elevation along the survey line
 fig.plot(
     x=track_df.p,
     y=track_df.elevation,
-    fill="gray",  # Fill the polygon in "gray"
-    # Draw a 1-point thick, black, solid outline
-    pen="1p,black,solid",
-    close="+y-8000",  # Force closed polygon
+    fill="gray",
+    pen="1p,red,solid",
+    close="+y-8000",
 )
 
+# Add map frame
+# Add annotations ("a") and ticks ("f") as well as labels ("+l") at the west or left
+# and south or bottom sides ("WSrt")
+fig.basemap(frame=["WSrt", "xa2f1+lDistance+u°", "ya4000+lElevation / m"])
+
 fig.show()