Note
Click here to download the full example code
Making your first figure¶
Welcome to PyGMT! Here we’ll cover some of basic concepts, like creating simple figures and naming conventions.
Note
This tutorial assumes the use of a Python notebook, such as IPython or Jupyter Notebook.
To see the figures while using a Python script instead, use
fig.show(method="external)
to display the figure in the default PDF viewer.
To save the figure, use fig.savefig("figname.pdf")
where "figname.pdf"
is the desired name and file extension for the saved figure.
Loading the library¶
All modules and figure generation is accessible from the pygmt
top level
package:
import pygmt
Creating figures¶
All figure generation in PyGMT is handled by the pygmt.Figure
class.
Start a new figure by creating an instance of this class:
fig = pygmt.Figure()
Add elements to the figure using its methods. For example, let’s start a map with an
automatic frame and ticks around a given longitude and latitude bound, set the
projection to Mercator (M
), and the map width to 8 inches:
fig.basemap(region=[-90, -70, 0, 20], projection="M8i", frame=True)
Now we can add coastlines using pygmt.Figure.coast
to this map using the
default resolution, line width, and color:
fig.coast(shorelines=True)
To see the figure, call pygmt.Figure.show
:
fig.show()
Out:
<IPython.core.display.Image object>
You can also set the map region, projection, and frame type directly in other methods
without calling gmt.Figure.basemap
:
fig = pygmt.Figure()
fig.coast(shorelines=True, region=[-90, -70, 0, 20], projection="M8i", frame=True)
fig.show()
Out:
<IPython.core.display.Image object>
Saving figures¶
Use the method pygmt.Figure.savefig
to save your figure to a file. The figure
format is inferred from the extension.
fig.savefig("central-america-shorelines.png")
Note for experienced GMT users¶
You’ll probably have noticed several things that are different from classic
command-line GMT. Many of these changes reflect the new GMT modern execution mode that
are part of GMT 6. A few are PyGMT exclusive (like the savefig
method).
The name of method is
coast
instead ofpscoast
. As a general rule, allps*
modules had theirps
prefix removed. The exceptions are:psxy
which is nowplot
,psxyz
which is nowplot3d
, andpsscale
which is nowcolorbar
.The arguments don’t use the GMT 1-letter syntax (R, J, B, etc). We use longer aliases for these arguments and have some Python exclusive names. The mapping between the GMT arguments and their Python counterparts should be straight forward.
Arguments like
region
can take lists as well as strings like1/2/3/4
.If a GMT argument has no options (like
-B
instead of-Baf
), use aTrue
in Python. An empty string would also be acceptable. For repeated arguments, such as-B+Loleron -Bxaf -By+lm
, provide a list:frame=["+Loleron", "xaf", "y+lm"]
.There is no output redirecting to a PostScript file. The figure is generated in the background and will only be shown or saved when you ask for it.
Total running time of the script: ( 0 minutes 3.124 seconds)