"""
Fill area between curves
========================
The :meth:`pygmt.Figure.fill_between` method fills the area between two curves y1 and
y2. Different fills (colors or patterns) can be used for the areas y1 > y2 and
y1 < y2. The two curves can be co-registered or have different x-coordinates. To plot
an anomaly along a track use :meth:`pygmt.Figure.wiggle` and see the gallery example
:doc:`Wiggle along tracks </gallery/lines/wiggle>`.

For filling the areas between the two curves use the ``fill`` and ``fill2`` parameters
to set different fills for the areas with y1 > y2 and y1 < y2, respectively. Use the
``label`` and ``label2`` parameters to set the corresponding legend entries. In addition
to filling the areas, we can draw the outline curves. Use the ``pen`` and  ``pen2``
parameters to set different lines for the two curves y1 and y2, respectively.

"""

# %%
import numpy as np
import pygmt

# Generate some test data
x = np.arange(-10, 10.2, 0.15)
y1 = np.sin(3 * x)
y2 = np.sin(x / 2)

x3 = np.arange(-10, 10.4, 0.5) - 0.13
y3 = np.sin(x3 / 2)


# %%
# To compare a curve y1(x) to a horizontal line, pass the desired y-level to ``y2``.

fig = pygmt.Figure()
fig.basemap(region=[-10, 10, -3.5, 3.5], projection="X15c/5c", frame=True)

fig.fill_between(
    x=x,
    y=y1,
    y2=0.42,
    fill="p8",
    fill2="p17",
    pen="1p,black,solid",
    pen2="1p,black,dashed",
)
fig.show()


# %%
# To compare two co-registered curves y1(x) and y2(x) pass a sequence with the same
# length as the inputs for ``x`` and ``y`` to ``y2``.

fig = pygmt.Figure()
fig.basemap(region=[-10, 10, -3.5, 3.5], projection="X15c/5c", frame=True)

fig.fill_between(
    x=x, y=y1, y2=y2, fill="orange", fill2="steelblue", label="y1(x)", label2="y2(x)"
)
fig.legend()
fig.show()


# %%
# Now, we use two non-co-registered curves, e.g., the two curves have different
# x-coordinates. For providing the x-coordinates for the second curve, use
# parameter ``x2``.  Via the ``legend_pen`` parameter the appearance in the legend
# can be changed to draw the legend entries as colored lines (using the fill colors)
# instead of filled and outlined boxes.

fig = pygmt.Figure()
fig.basemap(region=[-10, 10, -3.5, 3.5], projection="X15c/5c", frame=True)

fig.fill_between(
    x=x,
    y=y1,
    x2=x3,
    y2=y3,
    fill="orange",
    fill2="steelblue",
    pen="1p,darkred,solid",
    pen2="1p,darkblue,solid",
    label="y1(x)",
    label2="y3(x3)",
    legend_pen=True,
)

# Mark sampling points
fig.plot(x=x, y=y1, style="c0.1c", fill="pink")
fig.plot(x=x3, y=y3, style="c0.1c", fill="cyan")

fig.legend()
fig.show()

# sphinx_gallery_thumbnail_number = 3