"""
Contour lines
=============

Marching-squares contours of a 2-D field. Each level's own color comes from
its *value*, normalized by ``vmin``/``vmax`` -- the same normalization
``pcolormesh``/``contourf`` use over the same field, so an explicit
``vmin``/``vmax`` colors contour lines consistently with a filled version
of it (here, wider than ``Z``'s own +-1 range, so every line sits well
inside the colormap rather than spanning its full extent).
"""
import numpy as np
import plotpress

g = np.linspace(-3, 3, 120)
X, Y = np.meshgrid(g, g)
Z = np.sin(X) * np.cos(Y)
fig, ax = plotpress.subplots()
ax.contour(g, g, Z, levels=10, vmin=-2, vmax=2)
ax.set_title("contour")
fig.tight_layout()