Bit and hachure patterns

In addition to colors, PyGMT also allows using bit and hachure patterns to fill symbols, polygons, and other areas, via the fill parameter or similar parameters.

Example method parameters that support bit and hachure patterns include:

• pygmt.Figure.coast: Land and water masses via land and water

• pygmt.Figure.histogram: Histogram bars via fill

• pygmt.Figure.meca: Focal mechanisms via compressionfill and extensionfill

• pygmt.Figure.plot: Symbols and polygons via fill

• pygmt.Figure.rose: Histogram sectors via fill

• pygmt.Figure.solar: Day-light terminators via fill

• pygmt.Figure.ternary: Symbols via fill

• pygmt.Figure.velo: Uncertainty wedges and velocity error ellipses via uncertaintyfill

• pygmt.Figure.wiggle: Anomalies via fillpositive and fillnegative

GMT provides 90 predefined 1-bit patterns, which are numbered from 1 to 90. In addition, custom 1-, 8-, or 24-bit image raster files can also be used as patterns.

These patterns can be specified via the pygmt.params.Pattern class. The patterns can be customized with different resolution and different foreground and background colors. The foreground and background colors can also be inverted.

import pygmt
from pygmt.params import Pattern

# A list of patterns that will be demonstrated.
# By default, a pattern is plotted in black and white with a resolution of 300 dpi.
patterns = [
    # Predefined 1-bit pattern 8.
    Pattern(8),
    # Predefined 1-bit pattern 19.
    Pattern(19),
    # Pattern 19 with custom background ("red3") and foreground ("lightbrown").
    Pattern(19, bgcolor="red3", fgcolor="lightbrown"),
    # Invert the background and foreground.
    Pattern(19, invert=True, bgcolor="red3", fgcolor="lightbrown"),
    # Same as above, but with a 100 dpi resolution.
    Pattern(19, bgcolor="red3", fgcolor="lightbrown", dpi=100),
    # Same as above, but with a transparent background by setting bgcolor to "".
    Pattern(19, bgcolor="", fgcolor="lightbrown", dpi=100),
]

fig = pygmt.Figure()
fig.basemap(
    region=[0, 10, 0, 12],
    projection="X18c/10c",
    frame="rlbt+glightgray+tBit and Hachure Patterns",
)
y = 11
for pattern in patterns:
    # Plot a square with the pattern as fill.
    # The square has a size of 2 centimeters with a 1 point thick, black outline.
    fig.plot(x=1, y=y, style="s2c", pen="1p,black", fill=pattern)
    # Add a description of the pattern.
    fig.text(x=2, y=y, text=str(repr(pattern)), font="Courier-Bold", justify="ML")
    y -= 2
fig.show()