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https://github.com/joferkington/mplstereonet

Stereonets for matplotlib
https://github.com/joferkington/mplstereonet

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Stereonets for matplotlib

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mplstereonet

============

``mplstereonet`` provides lower-hemisphere equal-area and equal-angle stereonets

for matplotlib.



.. image:: http://joferkington.github.io/mplstereonet/images/equal_area_equal_angle_comparison.png

    :alt: Comparison of equal angle and equal area stereonets.

    :align: center

    :target: https://github.com/joferkington/mplstereonet/blob/master/examples/equal_area_equal_angle_comparison.py



Install

-------



``mplstereonet`` can be installed from PyPi using ``pip`` by::



    pip install mplstereonet



Alternatively, you can download the source and install locally using (from the

main directory of the repository)::



    python setup.py install



If you're planning on developing ``mplstereonet`` or would like to experiment

with making local changes, consider setting up a development installation so

that your changes are reflected when you import the package::



    python setup.py develop



Basic Usage

-----------

In most cases, you'll want to ``import mplstereonet`` and then make an axes

with ``projection="stereonet"`` (By default, this is an equal-area stereonet).

Alternately, you can use ``mplstereonet.subplots``, which functions identically

to ``matplotlib.pyplot.subplots``, but creates stereonet axes.



As an example::



    import matplotlib.pyplot as plt

    import mplstereonet



    fig = plt.figure()

    ax = fig.add_subplot(111, projection='stereonet')



    strike, dip = 315, 30

    ax.plane(strike, dip, 'g-', linewidth=2)

    ax.pole(strike, dip, 'g^', markersize=18)

    ax.rake(strike, dip, -25)

    ax.grid()



    plt.show()



.. image:: http://joferkington.github.io/mplstereonet/images/basic.png

    :alt: A basic stereonet with a plane, pole to the plane, and rake along the plane

    :align: center

    :target: https://github.com/joferkington/mplstereonet/blob/master/examples/basic.py

    

Planes, lines, poles, and rakes can be plotted using axes methods (e.g.

``ax.line(plunge, bearing)`` or ``ax.rake(strike, dip, rake_angle)``).



All planar measurements are expected to follow the right-hand-rule to indicate

dip direction. As an example, 315/30S would be 135/30 following the right-hand

rule.



Density Contouring

------------------

``mplstereonet`` also provides a few different methods of producing contoured

orientation density diagrams.



The ``ax.density_contour`` and ``ax.density_contourf`` axes methods provide density

contour lines and filled density contours, respectively.  "Raw" density grids

can be produced with the ``mplstereonet.density_grid`` function.



As a basic example::



    import matplotlib.pyplot as plt

    import numpy as np

    import mplstereonet

    

    fig, ax = mplstereonet.subplots()

    

    strike, dip = 90, 80

    num = 10

    strikes = strike + 10 * np.random.randn(num)

    dips = dip + 10 * np.random.randn(num)

    

    cax = ax.density_contourf(strikes, dips, measurement='poles')

                              

    ax.pole(strikes, dips)

    ax.grid(True)

    fig.colorbar(cax)

    

    plt.show()



.. image:: http://joferkington.github.io/mplstereonet/images/contouring.png

    :alt: Orientation density contours.

    :align: center

    :target: https://github.com/joferkington/mplstereonet/blob/master/examples/contouring.py



By default, a modified Kamb method with exponential smoothing [Vollmer1995]_ is

used to estimate the orientation density distribution. Other methods (such as

the "traditional" Kamb [Kamb1956]_ and "Schmidt" (a.k.a. 1%) methods) are

available as well. The method and expected count (in standard deviations) can

be controlled by the ``method`` and ``sigma`` keyword arguments, respectively.



.. image:: http://joferkington.github.io/mplstereonet/images/contour_angelier_data.png

    :alt: Orientation density contours.

    :align: center

    :target: https://github.com/joferkington/mplstereonet/blob/master/examples/contour_angelier_data.py



Utilities

---------

``mplstereonet`` also includes a number of utilities to parse structural

measurements in either quadrant or azimuth form such that they follow the

right-hand-rule. 



For an example, see parsing_example.py_::



    Parse quadrant azimuth measurements

    "N30E" --> 30.0

    "E30N" --> 60.0

    "W10S" --> 260.0

    "N 10 W" --> 350.0

    

    Parse quadrant strike/dip measurements.

    Note that the output follows the right-hand-rule.

    "215/10" --> Strike: 215.0, Dip: 10.0

    "215/10E" --> Strike: 35.0, Dip: 10.0

    "215/10NW" --> Strike: 215.0, Dip: 10.0

    "N30E/45NW" --> Strike: 210.0, Dip: 45.0

    "E10N   20 N" --> Strike: 260.0, Dip: 20.0

    "W30N/46.7 S" --> Strike: 120.0, Dip: 46.7

    

    Similarly, you can parse rake measurements that don't follow the RHR.

    "N30E/45NW 10NE" --> Strike: 210.0, Dip: 45.0, Rake: 170.0

    "210 45 30N" --> Strike: 210.0, Dip: 45.0, Rake: 150.0

    "N30E/45NW raking 10SW" --> Strike: 210.0, Dip: 45.0, Rake: 10.0



Additionally, you can find plane intersections and make other calculations by

combining utility functions.  See plane_intersection.py_ and

parse_anglier_data.py_ for examples.



Analysis

--------



``mplstereonet`` contains orientation data analysis methods, as well as

plotting functionality.  For example, you can `fit planes to girdles

`_

or `fit a pole to points

`_,

identify different `modes of conjugate sets of faults

`_,

or calculate `flattening values for Flinn plots

`_.



Full Documentation

------------------



Full documentation is available at https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html



References

----------



.. [Kamb1956] Kamb, 1959. Ice Petrofabric Observations from Blue Glacier,

       Washington, in Relation to Theory and Experiment. Journal of

       Geophysical Research, Vol. 64, No. 11, pp. 1891--1909.



.. [Vollmer1995] Vollmer, 1995. C Program for Automatic Contouring of Spherical

       Orientation Data Using a Modified Kamb Method. Computers &

       Geosciences, Vol. 21, No. 1, pp. 31--49.



.. _parsing_example.py: https://mplstereonet.readthedocs.io/en/latest/examples/parsing_example.html



.. _plane_intersection.py: https://mplstereonet.readthedocs.io/en/latest/examples/plane_intersection.html



.. _parse_anglier_data.py: https://mplstereonet.readthedocs.io/en/latest/examples/parse_angelier_data.html