Contours

The pygmt.Figure.contour method can plot contour lines from a table of points by direct triangulation. The data to the triangulation can by provided in one of three options:

1: x, y, z 1d data columns

2: data 2d data matrix with 3 columns corresponding to x, y, z

3: data path string to a file containing the x, y, z in a tabular format

The parameters levels and annotation are deciding on the contours intervals and intervals of the annotation on the contours respectively

Out:

<IPython.core.display.Image object>

import numpy as np
import pygmt

# building the contours underling data with the function z = x^2 + y^2
X, Y = np.meshgrid(np.linspace(-10, 10, 50), np.linspace(-10, 10, 50))
Z = X**2 + Y**2
x, y, z = X.flatten(), Y.flatten(), Z.flatten()


fig = pygmt.Figure()
fig.contour(
    region=[-10, 10, -10, 10],
    projection="X10c/10c",
    frame="ag",
    pen=1,
    # passing the data as 3 1d data columns
    x=x,
    y=y,
    z=z,
    # set the contours z values intervals to 5
    levels=5,
    # set the contours annotation intervals to 20
    annotation=20
)
fig.show()