Plotting single-parameter symbols

The pygmt.Figure.plot method can plot symbols via the style, size, and symbol parameters. This tutorial focuses on single-parameter symbols; for an overview of the available single-parameter symbols, see the Gallery example Single-parameter symbols. The available multi- parameter symbols are explained in the Gallery example Multi-parameter symbols.

import numpy as np
import pygmt

# Set up five sample data points as NumPy arrays for the x and y values
x = np.array([-4, -2, 0, 2, 4])
y = np.array([0, 0, 0, 0, 0])

Plot single-parameter symbols

Use the style parameter of the pygmt.Figure.plot method to plot all data points with the same symbol and size. By default, the symbol is drawn unfilled with an 0.25-points, thick, solid outline. Use the pen parameter to adjust the outline by providing a string argument in the form width,color,style; for details see the Gallery example Line styles.

fig = pygmt.Figure()
fig.basemap(region=[-5, 5, -2, 2], projection="X10c/4c", frame=True)

# Plot circles (first "c") with a diameter of 0.5 centimeters (second "c")
fig.plot(x=x, y=y, style="c0.5c")

fig.shift_origin(xshift="w+1c")
fig.basemap(region=[-5, 5, -2, 2], projection="X10c/4c", frame=True)

# Adjust the outline via the pen parameter
fig.plot(x=x, y=y, style="c0.5c", pen="1p,orange")

fig.show()

Use the fill the parameter to add a fill color or pattern. Note, that no outline is drawn by default when fill is used. For the available patterns see the Technical Reference Bit and hachure patterns.

fig = pygmt.Figure()
fig.basemap(region=[-5, 5, -2, 2], projection="X10c/4c", frame=True)

# Add a color via the fill parameter
fig.plot(x=x, y=y, style="c0.5c", fill="gray")

fig.shift_origin(xshift="w+1c")
fig.basemap(region=[-5, 5, -2, 2], projection="X10c/4c", frame=True)

# Add an outline via the pen parameter
fig.plot(x=x, y=y, style="c0.5c", fill="gray", pen="1p,orange")

fig.show()

Use individual sizes

Use the size parameter to plot the data points with individual sizes. Provide the different sizes as a NumPy array or array-like object of integers or floats.

fig = pygmt.Figure()
fig.basemap(region=[-5, 5, -2, 2], projection="X10c/4c", frame=True)

fig.plot(
    x=x,
    y=y,
    # Plot circles (first "c") with a diameter in centimeters (second "c")
    style="cc",
    # Use individual sizes
    size=np.array([0.5, 0.2, 0.4, 0.6, 0.3]),
    fill="gray",
    pen="1p,orange",
)

fig.show()

Use individual symbols

Use the symbol parameter to plot the data points with individual symbols. Provide the different symbols as a list of strings. Here, only single-parameter symbols can be used.

fig = pygmt.Figure()
fig.basemap(region=[-5, 5, -2, 2], projection="X10c/4c", frame=True)

fig.plot(
    x=x,
    y=y,
    # Use a constant size of 0.5 centimeters
    style="0.5c",
    # Plot a circle, a square, a triangle, an inverse triangle, a diamond
    symbol=["c", "s", "t", "i", "d"],
    fill="gray",
    pen="1p,orange",
)

fig.show()

Use individual symbols and sizes

Use the symbol and size parameters together to plot the data points with individual symbols and sizes. The arguments passed to symbol and size must have the same length. The unit for size is now set via the GMT default parameter PROJ_LENGTH_UNIT which can by adjusted using pygmt.config [Default is centimeters].

fig = pygmt.Figure()
fig.basemap(region=[-5, 5, -2, 2], projection="X10c/4c", frame=True)

fig.plot(
    x=x,
    y=y,
    symbol=["c", "s", "t", "i", "d"],
    size=np.array([0.5, 0.2, 0.4, 0.6, 0.3]),
    fill="gray",
    pen="1p,orange",
)

fig.show()