Add gallery example showing how to fill the area between two curves

examples/gallery/lines/curves_area.py

@@ -0,0 +1,59 @@
+"""
+Area between curves
+-------------------
+Using the ``fill_between`` parameter of the :meth:`pygmt.Figure.plot` method it is
+possible to fill the area between two curves y1 and y2 with color. Different fills
+(colors or patterns) can be used for the areas y1 > y2 and y1 < y2. Optionally, the
+curves can be drawn.
+"""
+
+# %%
+import numpy as np
+import pandas as pd
+import pygmt as gmt
+
+# -----------------------------------------------------------------------------
+# Generate some test data and create a pandas DataFrame
+x = np.arange(-10, 10.2, 0.1)
+y1 = np.sin(x * 3)
+y2 = np.sin(x / 2)
+
+data = np.array([x, y1, y2])
+data_tp = data.transpose()
+
+data_df = pd.DataFrame(data_tp, columns=["x", "y1", "y2"])
+
+# -----------------------------------------------------------------------------
+# Set up new Figure instance
+fig = gmt.Figure()
+fig.basemap(region=[-10, 10, -5, 5], projection="X15c/5c", frame=True)
+
+fig.plot(
+    data=data_df,
+    fill="orange",
+    fill_between="c+gsteelblue+lshort < long",
+    label="short > long",
+)
+
+fig.legend()
+
+fig.show()
+
+
+# %%
+# Additionally we can draw the curves.
+
+# Set up new Figure instance
+fig = gmt.Figure()
+fig.basemap(region=[-10, 10, -5, 5], projection="X15c/5c", frame=True)
+
+fig.plot(
+    data=data_df,
+    fill="p8",
+    pen="1p,black,solid",
+    fill_between="c+gp17+p1p,black,dashed",
+)
+
+fig.show()
+
+# sphinx_gallery_thumbnail_number = 1