"""
Creating a map with contour lines
=================================

Plotting a contour map is handled by :meth:`pygmt.Figure.grdcontour`.
"""

# %%
import pygmt

# Load sample earth relief data
grid = pygmt.datasets.load_earth_relief(resolution="05m", region=[-92.5, -82.5, -3, 7])


# %%
# Create contour plot
# -------------------
#
# The :meth:`pygmt.Figure.grdcontour` method takes the grid input.
# It plots annotated contour lines, which are thicker and have the
# elevation/depth written on them, and unannotated contour lines.
# In the example below, the default contour line intervals are 500 meters,
# with an annotated contour line every 1,000 meters.
# By default, it plots the map with the
# equidistant cylindrical projection and with no frame.

fig = pygmt.Figure()
fig.grdcontour(grid=grid)
fig.show()


# %%
# Contour line settings
# ---------------------
#
# Use the ``annotation`` and ``interval`` parameters to adjust contour line
# intervals. In the example below, there are contour intervals every 250 meters
# and annotated contour lines every 1,000 meters.

fig = pygmt.Figure()
fig.grdcontour(
    annotation=1000,
    interval=250,
    grid=grid,
)
fig.show()


# %%
# Contour limits
# --------------
#
# The ``limit`` parameter sets the minimum and maximum values for the contour
# lines. The parameter takes the low and high values, and is either a list (as
# below) or a string ``limit="-4000/-2000"``.

fig = pygmt.Figure()
fig.grdcontour(
    annotation=1000,
    interval=250,
    grid=grid,
    limit=[-4000, -2000],
)
fig.show()


# %%
# Map settings
# ------------
#
# The :meth:`pygmt.Figure.grdcontour` method accepts additional parameters,
# including setting the projection and frame.

fig = pygmt.Figure()
fig.grdcontour(
    annotation=1000,
    interval=250,
    grid=grid,
    limit=[-4000, -2000],
    projection="M10c",
    frame=True,
)
fig.show()


# %%
# Adding a colormap
# -----------------
#
# The :meth:`pygmt.Figure.grdimage` method can be used to add a
# colormap to the contour map. It must be called prior to
# :meth:`pygmt.Figure.grdcontour` to keep the contour lines visible on the
# final map. If the ``projection`` parameter is specified in the
# :meth:`pygmt.Figure.grdimage` method, it does not need to be repeated in the
# :meth:`pygmt.Figure.grdcontour` method. Finally, a colorbar is added using
# the :meth:`pygmt.Figure.colorbar` method.

fig = pygmt.Figure()
fig.grdimage(
    grid=grid,
    cmap="haxby",
    projection="M10c",
    frame=True,
)
fig.grdcontour(
    annotation=1000,
    interval=250,
    grid=grid,
    limit=[-4000, -2000],
)
fig.colorbar(frame=["x+lelevation", "y+lm"])
fig.show()

# sphinx_gallery_thumbnail_number = 5