.. _example_07:

(7) A simple location map
-------------------------

Many scientific papers start out by showing a location map of the region
of interest. This map will typically also contain certain features and
labels. This example will present a location map for the equatorial
Atlantic ocean, where fracture zones and mid-ocean ridge segments have
been plotted. We also would like to plot earthquake locations and
available isochrons. We have obtained one file, ``quakes.xym``, which contains the
position and magnitude of available earthquakes in the region. We choose
to use magnitude/100 for the symbol-size in inches. The digital fracture
zone traces (``fz.xy``) and isochrons (0 isochron as ``ridge.xy``, the rest as ``isochrons.xy``) were
digitized from available maps [1]_. We create the final location map
with the following script:

.. literalinclude:: /_verbatim/example_07.txt
   :language: bash

The same figure could equally well be made in color, which could be
rasterized and made into a slide for a meeting presentation. The script
is similar to the one outlined above, except we would choose a color for
land and oceans, and select colored symbols and pens rather than black
and white.

.. figure:: /_images/example_07.*
   :width: 500 px
   :align: center

   A typical location map.

.. [1]
   These data are available on CD-ROM from NGDC (www.ngdc.noaa.gov).
