Frames, ticks, titles, and labels

Setting the style of the map frames, ticks, etc, is handled by the frame argument that all plotting methods of pygmt.Figure.

import pygmt

Plot frame

By default, PyGMT does not add a frame to your plot. For example, we can plot the coastlines of the world with a Mercator projection:

fig = pygmt.Figure()
fig.coast(shorelines="1/0.5p", region=[-180, 180, -60, 60], projection="M25c")
fig.show()

Out:

<IPython.core.display.Image object>

To add the default GMT frame to the plot, use frame="f" in pygmt.Figure.basemap or any other plotting module:

fig = pygmt.Figure()
fig.coast(shorelines="1/0.5p", region=[-180, 180, -60, 60], projection="M25c")
fig.basemap(frame="f")
fig.show()

Out:

<IPython.core.display.Image object>

Ticks and grid lines

The automatic frame (frame=True or frame="a") sets the default GMT style frame and automatically determines tick labels from the plot region.

fig = pygmt.Figure()
fig.coast(shorelines="1/0.5p", region=[-180, 180, -60, 60], projection="M25c")
fig.basemap(frame="a")
fig.show()

Out:

<IPython.core.display.Image object>

Add automatic grid lines to the plot by adding a g to frame:

fig = pygmt.Figure()
fig.coast(shorelines="1/0.5p", region=[-180, 180, -60, 60], projection="M25c")
fig.basemap(frame="ag")
fig.show()

Out:

<IPython.core.display.Image object>

Title

The figure title can be set by passing +ttitle to the frame parameter of pygmt.Figure.basemap. Passing multiple arguments to frame can be done by using a list, as show in the example below.

fig = pygmt.Figure()
# region="IS" specifies Iceland using the ISO country code
fig.coast(shorelines="1/0.5p", region="IS", projection="M25c")
fig.basemap(frame=["a", "+tIceland"])
fig.show()

Out:

<IPython.core.display.Image object>

To use a title with multiple words, the title must be placed inside another set of quotation marks. To prevent the quotation marks from appearing in the figure title, the frame argument can be passed in single quotation marks and the title can be passed in double quotation marks.

fig = pygmt.Figure()
# region="TT" specifies Trinidad and Tobago
fig.coast(shorelines="1/0.5p", region="TT", projection="M25c")
fig.basemap(frame=["a", '+t"Trinidad and Tobago"'])
fig.show()

Out:

<IPython.core.display.Image object>

Axis labels

Axis labels can be set by passing x+llabel (or starting with y if labeling the y-axis) if to the frame parameter of pygmt.Figure.basemap. Axis labels will be displayed on all primary axes, which the default is all sides of the figure. To designate only some of the axes as primary, an argument that capitlizes only the primary axes can be passed, which is "WSne" in the example below. The letters correspond with west (left), south (bottom), north (top), and east (right) sides of a figure.

The example below used a Cartesian projection, as GMT does not allow axis labels to be set for geographic maps.

fig = pygmt.Figure()
fig.basemap(
    region=[0, 10, 0, 20],
    projection="X10c/8c",
    frame=["WSne", "x+lx-axis", "y+ly-axis"],
)
fig.show()

Out:

<IPython.core.display.Image object>