"""Adding a citation for a plot using iris.plot.citation()."""

import matplotlib.pyplot as plt

import iris
import iris.plot as iplt
import iris.quickplot as qplt

fname = iris.sample_data_path("air_temp.pp")
temperature_cube = iris.load_cube(fname)

# Get the Purples "Brewer" palette.
brewer_cmap = plt.get_cmap("brewer_Purples_09")

# Draw the contours, with n-levels set for the map colours (9).
# NOTE: needed as the map is non-interpolated, but matplotlib does not provide
# any special behaviour for these.
qplt.contourf(temperature_cube, brewer_cmap.N, cmap=brewer_cmap)

# Add a citation to the plot.
iplt.citation(iris.plot.BREWER_CITE)

# Add coastlines to the map created by contourf.
plt.gca().coastlines()

plt.show()