mplstereonet

https://mplstereonet.readthedocs.io/en/latest/
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### Local installation from source

Source: https://mplstereonet.readthedocs.io/en/latest/index.html

Installs mplstereonet locally from the source code.

```bash
python setup.py install

```

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

### Installation with pip

Source: https://mplstereonet.readthedocs.io/en/latest/index.html

Installs the mplstereonet package using pip.

```bash
pip install mplstereonet

```

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

### Development installation

Source: https://mplstereonet.readthedocs.io/en/latest/index.html

Sets up a development installation of mplstereonet, reflecting local changes.

```bash
python setup.py develop

```

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

### Parse Plunge Bearing Example

Source: https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html

Example demonstrating how to parse plunge and bearing values.

```python
>>> parse_plunge_bearing("30NW", 160)
... (30, 340)

```

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

### Basic Usage Example

Source: https://mplstereonet.readthedocs.io/en/latest/index.html

Demonstrates basic usage of mplstereonet by plotting a plane, pole, and rake, and showing a grid.

```python
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()

```

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

### Parsing Example

Source: https://mplstereonet.readthedocs.io/en/latest/index.html

Illustrates parsing structural measurements in quadrant or azimuth form using mplstereonet utilities.

```python
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

```

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

### Grid Line Properties

Source: https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html

Example of defining line properties for the grid using keyword arguments.

```python
grid(color='r', linestyle='-', linewidth=2)
```

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

### Fault Slip Plot Example

Source: https://mplstereonet.readthedocs.io/en/latest/examples/fault_slip_plot.html

Demonstrates plotting fault slip data using both the fault-and-striae and tangent lineation methods with mplstereonet.

```python
import matplotlib.pyplot as plt
import numpy as np
import mplstereonet

import parse_angelier_data

def main():
    # Load data from Angelier, 1979
    strikes, dips, rakes = parse_angelier_data.load()

    params = dict(projection='stereonet', azimuth_ticks=[])
    fig, (ax1, ax2) = plt.subplots(ncols=2, subplot_kw=params)

    fault_and_striae_plot(ax1, strikes, dips, rakes)
    ax1.set_title('Fault-and-Striae Diagram')
    ax1.set_xlabel('Lineation direction plotted\nat rake location on plane')

    tangent_lineation_plot(ax2, strikes, dips, rakes)
    ax2.set_title('Tangent Lineation Diagram')
    ax2.set_xlabel('Lineation direction plotted\nat pole location of plane')

    fig.suptitle('Fault-slip data from Angelier, 1979', y=0.05)
    fig.tight_layout()

    plt.show()

def fault_and_striae_plot(ax, strikes, dips, rakes):
    """Makes a fault-and-striae plot (a.k.a. "Ball of String") for normal faults
    with the given strikes, dips, and rakes."""
    # Plot the planes
    lines = ax.plane(strikes, dips, 'k-', lw=0.5)

    # Calculate the position of the rake of the lineations, but don't plot yet
    x, y = mplstereonet.rake(strikes, dips, rakes)

    # Calculate the direction the arrows should point
    # These are all normal faults, so the arrows point away from the center
    # For thrusts, it would just be u, v = -x/mag, -y/mag
    mag = np.hypot(x, y)
    u, v = x / mag, y / mag

    # Plot the arrows at the rake locations...
    arrows = ax.quiver(x, y, u, v, width=1, headwidth=4, units='dots')
    return lines, arrows

def tangent_lineation_plot(ax, strikes, dips, rakes):
    """Makes a tangent lineation plot for normal faults with the given strikes,
    dips, and rakes."""
    # Calculate the position of the rake of the lineations, but don't plot yet
    rake_x, rake_y = mplstereonet.rake(strikes, dips, rakes)

    # Calculate the direction the arrows should point
    # These are all normal faults, so the arrows point away from the center
    # Because we're plotting at the pole location, however, we need to flip this
    # from what we plotted with the "ball of string" plot.
    mag = np.hypot(rake_x, rake_y)
    u, v = -rake_x / mag, -rake_y / mag

    # Calculate the position of the poles
    pole_x, pole_y = mplstereonet.pole(strikes, dips)

    # Plot the arrows centered on the pole locations...
    arrows = ax.quiver(pole_x, pole_y, u, v, width=1, headwidth=4, units='dots',
                       pivot='middle')
    return arrows

if __name__ == '__main__':
    main()

```

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

### `basic.py`

Source: https://mplstereonet.readthedocs.io/en/latest/examples/basic.html

As an example of basic functionality, let's plot a plane, the pole to the plane, and a rake along the plane.

```python
import matplotlib.pyplot as plt
import mplstereonet

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

# Measurements follow the right-hand-rule to indicate dip direction
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()

```

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

### `rotation_example.py`

Source: https://mplstereonet.readthedocs.io/en/latest/examples/rotation_example.html

This example demonstrates plotting a plane, its pole, and a rake along the plane using mplstereonet. It shows how to plot on both un-rotated and rotated stereonet axes.

```python
import matplotlib.pyplot as plt
import mplstereonet

fig = plt.figure()

# An un-rotated axes
ax1 = fig.add_subplot(121, projection='stereonet')

# Rotated 30 degrees clockwise from North
ax2 = fig.add_subplot(122, projection='stereonet', rotation=30)

# Measurements follow the right-hand-rule to indicate dip direction
strike, dip = 315, 30

# Plot the same data on both axes
for ax in [ax1, ax2]:
    ax.plane(strike, dip, 'g-', linewidth=2)
    ax.pole(strike, dip, 'g^', markersize=18)
    ax.rake(strike, dip, -25)

    ax.grid()

plt.show()

```

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

### Density Contouring Example

Source: https://mplstereonet.readthedocs.io/en/latest/index.html

Shows how to create density contour plots using mplstereonet, including plotting poles and adding a color bar.

```python
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()

```

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

### Parsing Example

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

Demonstrates parsing of quadrant azimuth, strike/dip, and rake measurements using mplstereonet functions. It shows how to handle measurements that may not strictly follow the right-hand-rule.

```python
import mplstereonet

print('Parse quadrant azimuth measurements')
for original in ['N30E', 'E30N', 'W10S', 'N 10 W']:
    azi = mplstereonet.parse_quadrant_measurement(original)
    print('"{}" --> {:.1f}'.format(original, azi))

print('\nParse quadrant strike/dip measurements.')
print('Note that the output follows the right-hand-rule.')

def parse_sd(original, seperator):
    strike, dip = mplstereonet.parse_strike_dip(*original.split(seperator))
    print('"{}" --> Strike: {:.1f}, Dip: {:.1f}'.format(original, strike, dip))

parse_sd('215/10', '/')
parse_sd('215/10E', '/')
parse_sd('215/10NW', '/')
parse_sd('N30E/45NW', '/')
parse_sd('E10N\t20 N', '\t')
parse_sd('W30N/46.7 S', '/')

print("\nSimilarly, you can parse rake measurements that don't follow the RHR.")

def split_rake(original, sep1=None, sep2=None):
    components = original.split(sep1)
    if len(components) == 3:
        return components
    strike, rest = components
    dip, rake = rest.split(sep2)
    return strike, dip, rake

def display_rake(original, sep1, sep2=None):
    components = split_rake(original, sep1, sep2)
    strike, dip, rake = mplstereonet.parse_rake(*components)
    template = '"{}" --> Strike: {:.1f}, Dip: {:.1f}, Rake: {:.1f}'
    print(template.format(original, strike, dip, rake))

original = 'N30E/45NW 10NE'
display_rake(original, '/')

original = '210 45\t30N'
display_rake(original, None)

original = 'N30E/45NW raking 10SW'
display_rake(original, '/', 'raking')

```

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

### Find the average strike/dip of a series of bedding measurements

Source: https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html

Example showing how to find the average strike and dip from a series of bedding measurements using the fit_pole function.

```python
>>> strike = [270, 65, 280, 300]
>>> dip = [20, 15, 10, 5]
>>> strike0, dip0 = mplstereonet.fit_pole(strike, dip)
```

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

### `contouring.py`

Source: https://mplstereonet.readthedocs.io/en/latest/examples/contouring.html

A basic example of producing a density contour plot of poles to planes.

```python
import matplotlib.pyplot as plt
import numpy as np
import mplstereonet

# Fix random seed so that output is consistent
np.random.seed(1977)

fig, ax = mplstereonet.subplots()

# Generate a random scatter of planes around the given plane
# All measurements follow the right-hand-rule to indicate dip direction
strike, dip = 90, 80
num = 10
strikes = strike + 10 * np.random.randn(num)
dips = dip + 10 * np.random.randn(num)

# Create filled contours of the poles of the generated planes...
# By default this uses a modified Kamb contouring technique with exponential
# smoothing (See Vollmer, 1995)
cax = ax.density_contourf(strikes, dips, measurement='poles')

# Plot the poles as points on top of the contours
ax.pole(strikes, dips)

# Turn on a grid and add a colorbar
ax.grid(True)
fig.colorbar(cax)
plt.show()

```

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

### dip_direction2strike function example

Source: https://mplstereonet.readthedocs.io/en/latest/_modules/mplstereonet/utilities.html

Provides an example of dip_direction2strike, which converts a dip direction measurement (azimuth convention) into a strike measurement (right-hand-rule convention).

```python
def dip_direction2strike(azimuth):
    """
    Converts a planar measurment of dip direction using the dip-azimuth
    convention into a strike using the right-hand-rule.

    Parameters
    ----------
    azimuth : number or string
        The dip direction of the plane in degrees. This can be either a
        numerical azimuth in the 0-360 range or a string representing a quadrant
        measurement (e.g. N30W).

    Returns
    -------
    strike : number
        The strike of the plane in degrees following the right-hand-rule.
    """
    azimuth = parse_azimuth(azimuth)
    strike = azimuth - 90
    if strike < 0:
        strike += 360
    return strike
```

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

### Calculate the plunge of a cylindrical fold axis

Source: https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html

Example demonstrating how to calculate the plunge of a cylindrical fold axis from strike and dip measurements of bedding.

```python
>>> strike = [270, 334, 270, 270]
>>> dip = [20, 15, 80, 78]
>>> s, d = mplstereonet.fit_girdle(strike, dip)
>>> plunge, bearing = mplstereonet.pole2plunge_bearing(s, d)
```

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

### Plot filled density contours of a set of rake measurements.

Source: https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html

This example illustrates plotting filled density contours for rake measurements.

```python
>>> strikes, dips, rakes = [120, 315, 86], [22, 85, 31], [-5, 20, 9]
>>> ax.density_contourf(strikes, dips, rakes, measurement='rakes')
```

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

### Plot filled density contours of a set of linear orientation measurements.

Source: https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html

This example shows how to plot filled density contours for linear orientation measurements.

```python
>>> plunges, bearings = [-10, 20, -30], [120, 315, 86]
>>> ax.density_contourf(plunges, bearings, measurement='lines')
```

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

### Plot density contours of a set of rake measurements.

Source: https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html

This example illustrates plotting density contours for rake measurements, requiring strikes, dips, and rakes as input.

```python
>>> strikes, dips, rakes = [120, 315, 86], [22, 85, 31], [-5, 20, 9]
>>> ax.density_contour(strikes, dips, rakes, measurement='rakes')
```

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

### `fit_girdle_example.py`

Source: https://mplstereonet.readthedocs.io/en/latest/examples/fit_girdle_example.html

Illustrates fitting a plane to a “gridle” distribution using `fit_girdle`. This example simulates finding the plunge and bearing of a cylindrical fold axis from strike/dip measurements of bedding in the fold limbs.

```python
import numpy as np
import matplotlib.pyplot as plt
import mplstereonet
np.random.seed(1)

# Generate a random girdle distribution from the plunge/bearing of a fold hinge
# In the end, we'll have strikes and dips as measured from bedding in the fold.
# *strike* and *dip* below would normally be your input.
num_points = 200
real_bearing, real_plunge = 300, 5
s, d = mplstereonet.plunge_bearing2pole(real_plunge, real_bearing)
lon, lat = mplstereonet.plane(s, d, segments=num_points)
lon += np.random.normal(0, np.radians(15), lon.shape)
lat += np.random.normal(0, np.radians(15), lat.shape)
strike, dip = mplstereonet.geographic2pole(lon, lat)

# Plot the raw data and contour it:
fig, ax = mplstereonet.subplots()
ax.density_contourf(strike, dip, cmap='gist_earth')
ax.density_contour(strike, dip, colors='black')
ax.pole(strike, dip, marker='.', color='black')

# Fit a plane to the girdle of the distribution and display it.
fit_strike, fit_dip = mplstereonet.fit_girdle(strike, dip)
ax.plane(fit_strike, fit_dip, color='red', lw=2)
ax.pole(fit_strike, fit_dip, marker='o', color='red', markersize=14)

# Add some annotation of the result
lon, lat = mplstereonet.pole(fit_strike, fit_dip)
(plunge,), (bearing,) = mplstereonet.pole2plunge_bearing(fit_strike, fit_dip)
template = u'P/B of Fold Axis\n{:02.0f}\u00b0/{:03.0f}\u00b0'
ax.annotate(template.format(plunge, bearing), ha='center', va='bottom',
            xy=(lon, lat), xytext=(-50, 20), textcoords='offset points',
            arrowprops=dict(arrowstyle='-|>', facecolor='black'))

plt.show()

```

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

### `fisher_stats.py`

Source: https://mplstereonet.readthedocs.io/en/latest/examples/fisher_stats.html

This example shows how the Fisher statistics can be computed and displayed. It includes plotting the data, calculating Fisher statistics, and displaying the mean vector and confidence cone.

```python
import matplotlib.pyplot as plt
import mplstereonet as mpl

decl = [122.5, 130.5, 132.5, 148.5, 140.0, 133.0, 157.5, 153.0, 140.0, 147.5,
        142.0, 163.5, 141.0, 156.0, 139.5, 153.5, 151.5, 147.5, 141.0, 143.5,
        131.5, 147.5, 147.0, 149.0, 144.0, 139.5]
incl = [55.5, 58.0, 44.0, 56.0, 63.0, 64.5, 53.0, 44.5, 61.5, 54.5, 51.0, 56.0,
        59.5, 56.5, 54.0, 47.5, 61.0, 58.5, 57.0, 67.5, 62.5, 63.5, 55.5, 62.0,
        53.5, 58.0]
confidence = 95

fig = plt.figure()
ax = fig.add_subplot(111, projection='stereonet')
ax.line(incl, decl, color="black", markersize=2)

vector, stats = mpl.find_fisher_stats(incl, decl, conf=confidence)

template = (u"Mean Vector P/B: {plunge:0.0f}\\u00B0/{bearing:0.0f}\\u00B0\n"
            "Confidence: {conf}%\n"
            u"Fisher Angle: {fisher:0.2f}\\u00B0\n"
            u"R-Value {r:0.3f}\n"
            "K-Value: {k:0.2f}")

label = template.format(plunge=vector[0], bearing=vector[1], conf=confidence,
                        r=stats[0], fisher=stats[1], k=stats[2])

ax.line(vector[0], vector[1], color="red", label=label)
ax.cone(vector[0], vector[1], stats[1], facecolor="None", edgecolor="red")

ax.legend(bbox_to_anchor=(1.1, 1.1), numpoints=1)
plt.show()

```

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

### Plot density contours of a set of linear orientation measurements.

Source: https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html

This example shows how to plot density contours for linear orientation measurements, specifying 'lines' as the measurement type.

```python
>>> plunges, bearings = [-10, 20, -30], [120, 315, 86]
>>> ax.density_contour(plunges, bearings, measurement='lines')
```

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

### Plot density contours of poles to planes with contours at [1,2,3] standard deviations.

Source: https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html

This example demonstrates plotting density contours with specified contour levels representing standard deviations.

```python
>>> strikes, dips = [120, 315, 86], [22, 85, 31]
>>> ax.density_contour(strikes, dips, levels=[1,2,3])
```

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

### Plot filled density contours of poles to planes using a Kamb method with the density estimated on a 10x10 grid.

Source: https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html

This example shows plotting filled density contours with a specified Kamb method and grid size.

```python
>>> strikes, dips = [120, 315, 86], [22, 85, 31]
>>> ax.density_contourf(strikes, dips, method='kamb', gridsize=10)
```

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

### Find the eigenvectors as plunge/bearing and eigenvalues of the 3D covariance matrix of a series of planar measurements

Source: https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html

This example demonstrates how to use the `mplstereonet.eigenvectors` function to calculate eigenvectors and eigenvalues from strike and dip data.

```python
>>> strikes = [270, 65, 280, 300]
>>> dips = [20, 15, 10, 5]
>>> plu, azi, vals = mplstereonet.eigenvectors(strikes, dips)

```

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

### Plot filled density contours of poles to planes with contours at specified standard deviations.

Source: https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html

This example demonstrates plotting filled density contours with custom contour levels defined by standard deviations.

```python
>>> strikes, dips = [120, 315, 86], [22, 85, 31]
>>> ax.density_contourf(strikes, dips, levels=[1,2,3])
```

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

### Cross Section Plane Example

Source: https://mplstereonet.readthedocs.io/en/latest/examples/cross_section_plane.html

Plots two planes as great circles and poles, calculates the best fitting plane using `fit_girdle`, and visualizes the results.

```python
import matplotlib.pyplot as plt
import numpy as np
import mplstereonet

fig, ax = mplstereonet.subplots()

dip_directions = [100, 200]
dips = [30, 40]
strikes = np.array(dip_directions) - 90

ax.pole(strikes, dips, "bo")
ax.plane(strikes, dips, color='black', lw=1)

fit_strike, fit_dip = mplstereonet.fit_girdle(strikes, dips)

ax.plane(fit_strike, fit_dip, color='red', lw=1)
ax.pole(fit_strike, fit_dip, marker='o', color='red', markersize=5)

plt.show()

```

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

### parse_strike_dip function example

Source: https://mplstereonet.readthedocs.io/en/latest/_modules/mplstereonet/utilities.html

Demonstrates how parse_strike_dip converts string inputs for strike and dip into numerical azimuth and dip values, following the right-hand-rule.

```python
import numpy as np
import re
from . import stereonet_math as smath

def parse_strike_dip(strike, dip):
    """
    Parses strings of strike and dip and returns strike and dip measurements
    following the right-hand-rule.

    Dip directions are parsed, and if the measurement does not follow the
    right-hand-rule, the opposite end of the strike measurement is returned.

    Accepts either quadrant-formatted or azimuth-formatted strikes.

    For example, this would convert a strike of "N30E" and a dip of "45NW" to
    a strike of 210 and a dip of 45.

    Parameters
    ----------
    strike : string
        A strike measurement. May be in azimuth or quadrant format.
    dip : string
        The dip angle and direction of a plane.

    Returns
    -------
    azi : float
        Azimuth in degrees of the strike of the plane with dip direction
        indicated following the right-hand-rule.
    dip : float
        Dip of the plane in degrees.
    """
    strike = parse_azimuth(strike)
    dip, direction = split_trailing_letters(dip)

    if direction is not None:
        expected_direc = strike + 90
        if opposite_end(expected_direc, direction):
            strike += 180

    if strike > 360:
        strike -= 360

    return strike, dip
```

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

### Plot density contours of poles to the specified planes using a modified Kamb method with exponential smoothing [1].

Source: https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html

This example demonstrates plotting density contours of poles to planes using the default exponential Kamb method.

```python
>>> strikes, dips = [120, 315, 86], [22, 85, 31]
>>> ax.density_contour(strikes, dips)
```

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

### Plot density contours of a set of “raw” longitudes and latitudes.

Source: https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html

This example demonstrates plotting density contours using raw longitude and latitude data, specifying 'radians' as the measurement type.

```python
>>> lon, lat = np.radians([-40, 30, -85]), np.radians([21, -59, 45])
>>> ax.density_contour(lon, lat, measurement='radians')
```

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

### parse_plunge_bearing function example

Source: https://mplstereonet.readthedocs.io/en/latest/_modules/mplstereonet/utilities.html

Shows how parse_plunge_bearing processes plunge and bearing string inputs into consistent float values, ensuring plunge angles are between 0 and 90 degrees.

```python
def parse_plunge_bearing(plunge, bearing):
    """
    Parses strings of plunge and bearing and returns a consistent plunge and
    bearing measurement as floats. Plunge angles returned by this function will
    always be between 0 and 90.

    If no direction letter(s) is present, the plunge is assumed to be measured
    from the end specified by the bearing. If a direction letter(s) is present,
    the bearing will be switched to the opposite (180 degrees) end if the
    specified direction corresponds to the opposite end specified by the
    bearing.

    Parameters
    ----------
    plunge : string
        A plunge measurement.
    bearing : string
        A bearing measurement. May be in azimuth or quadrant format.

    Returns
    -------
    plunge, bearing: floats
        The plunge and bearing following the conventions outlined above.

    Examples
    ---------

        >>> parse_plunge_bearing("30NW", 160)
        ... (30, 340)

    """
    bearing = parse_azimuth(bearing)
    plunge, direction = split_trailing_letters(plunge)

    if direction is not None:
        if opposite_end(bearing, direction):
            bearing +=180

    if plunge < 0:
        bearing += 180
        plunge = -plunge
    if plunge > 90:
        bearing += 180
        plunge = 180 - plunge

    if bearing > 360:
        bearing -= 360

    return plunge, bearing
```

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

### Plot filled density contours of a set of “raw” longitudes and latitudes.

Source: https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html

This example demonstrates plotting filled density contours for raw longitude and latitude measurements, requiring conversion to radians.

```python
>>> lon, lat = np.radians([-40, 30, -85]), np.radians([21, -59, 45])
>>> ax.density_contourf(lon, lat, measurement='radians')
```

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

### angular_distance examples

Source: https://mplstereonet.readthedocs.io/en/latest/_modules/mplstereonet/stereonet_math.html

Examples of calculating angular distance between linear features and planes.

```python
    >>> angle = angular_distance(line(30, 270), line(40, 90))
    >>> np.degrees(angle)
    array([ 70.])
```

```python
    >>> first, second = line(30, 270), line(40, 90)
    >>> angle = angular_distance(first, second, bidirectional=False)
    >>> np.degrees(angle)
    array([ 110.])
```

```python
    >>> angle = angular_distance(pole(0, 10), pole(180, 10))
    >>> np.degrees(angle)
    array([ 20.])
```

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

### `scatter.py`

Source: https://mplstereonet.readthedocs.io/en/latest/examples/scatter.html

Example of how ax.scatter can be used to plot linear data on a stereonet varying color and/or size by other variables. This also serves as a general example of how to convert orientation data into the coordinate system that the stereonet plot uses so that generic matplotlib plotting methods may be used.

```python
import numpy as np
import matplotlib.pyplot as plt
import mplstereonet
np.random.seed(1)

strikes = np.arange(0, 360, 15)
dips = 45 * np.ones(strikes.size)
magnitude = np.random.random(strikes.size)

# Convert our strikes and dips to stereonet coordinates
lons, lats = mplstereonet.pole(strikes, dips)

# Now we'll plot our data and color by magnitude
fig, ax = mplstereonet.subplots()
sm = ax.scatter(lons, lats, c=magnitude, s=50, cmap='gist_earth')

ax.grid()
plt.show()

```

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

### Getting Azimuth Ticks

Source: https://mplstereonet.readthedocs.io/en/latest/_modules/mplstereonet/stereonet_axes.html

Retrieves the current azimuth tick locations.

```python
    def get_azimuth_ticks(self, minor=False):
        return self._polar.get_xticks(minor)
```

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

### Getting Azimuth Tick Labels

Source: https://mplstereonet.readthedocs.io/en/latest/_modules/mplstereonet/stereonet_axes.html

Retrieves the azimuth tick labels as a list of Text artists.

```python
    def get_azimuth_ticklabels(self, minor=False):
        """Get the azimuth tick labels as a list of Text artists."""
        return self._polar.get_xticklabels(minor)
```

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

### Plot density contours of a set of rake measurements.

Source: https://mplstereonet.readthedocs.io/en/latest/_modules/mplstereonet/stereonet_axes.html

This example illustrates plotting density contours for rake measurements.

```python
strikes, dips, rakes = [120, 315, 86], [22, 85, 31], [-5, 20, 9]
ax.density_contour(strikes, dips, rakes, measurement='rakes')
```

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

### Plot density contours of a set of linear orientation measurements.

Source: https://mplstereonet.readthedocs.io/en/latest/_modules/mplstereonet/stereonet_axes.html

This example shows how to plot density contours for linear orientation measurements.

```python
plunges, bearings = [-10, 20, -30], [120, 315, 86]
ax.density_contour(plunges, bearings, measurement='lines')
```

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

### Plot filled density contours of poles to the specified planes using a modified Kamb method with exponential smoothing.

Source: https://mplstereonet.readthedocs.io/en/latest/mplstereonet.html

This example demonstrates plotting filled density contours for poles to planes using the density_contourf function with default parameters.

```python
>>> strikes, dips = [120, 315, 86], [22, 85, 31]
>>> ax.density_contourf(strikes, dips)
```

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

### K-means clustering for fault sets

Source: https://mplstereonet.readthedocs.io/en/latest/examples/kmeans_example.html

This code snippet demonstrates how to use the `mplstereonet.kmeans` function to find the average strike and dip of two conjugate fault sets. It loads data, plots the raw data and contours, identifies the two modes using k-means, and annotates the results on the stereonet plot.

```python
import matplotlib.pyplot as plt
import mplstereonet

import parse_angelier_data

# Load data from Angelier, 1979
strike, dip, rake = parse_angelier_data.load()

# Plot the raw data and contour it:
fig, ax = mplstereonet.subplots()
#ax.density_contourf(strike, dip, rake, measurement='rakes', cmap='gist_earth',
#                    sigma=1.5)
ax.density_contour(strike, dip, rake, measurement='rakes', cmap='gist_earth',
                    sigma=1.5)
ax.rake(strike, dip, rake, marker='.', color='black')

# Find the two modes
centers = mplstereonet.kmeans(strike, dip, rake, num=2, measurement='rakes')
strike_cent, dip_cent = mplstereonet.geographic2pole(*zip(*centers))
ax.pole(strike_cent, dip_cent, 'ro', ms=12)

# Label the modes
for (x0, y0) in centers:
    s, d = mplstereonet.geographic2pole(x0, y0)
    x, y = mplstereonet.pole(s, d) # Otherwise, we may get the antipode...

    if x > 0:
        kwargs = dict(xytext=(40, -40), ha='left')
    else:
        kwargs = dict(xytext=(-40, 40), ha='right')

    ax.annotate('{:03.0f}/{:03.0f}'.format(s[0], d[0]), xy=(x, y),
                xycoords='data', textcoords='offset points',
                arrowprops=dict(arrowstyle='->', connectionstyle='angle3'),
                **kwargs)

ax.set_title('Strike/dip of conjugate fault sets', y=1.07)

plt.show()

```

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

### Contour Angellier Data Example

Source: https://mplstereonet.readthedocs.io/en/latest/examples/contour_angelier_data.html

This code snippet demonstrates how to reproduce Figure 5 from Vollmer, 1995, illustrating different density contouring methods using mplstereonet and parse_angelier_data.

```python
import matplotlib.pyplot as plt
import mplstereonet

import parse_angelier_data

def plot(ax, strike, dip, rake, **kwargs):
    ax.rake(strike, dip, rake, 'ko', markersize=2)
    ax.density_contour(strike, dip, rake, measurement='rakes', linewidths=1,
                       cmap='jet', **kwargs)


# Load data from Angelier, 1979
strike, dip, rake = parse_angelier_data.load()

# Setup a subplot grid
fig, axes = mplstereonet.subplots(nrows=3, ncols=4)

# Hide azimuth tick labels
for ax in axes.flat:
    ax.set_azimuth_ticks([])

contours = [range(2, 18, 2), range(1, 21, 2), range(1, 22, 2)]

# "Standard" Kamb contouring with different confidence levels.
for sigma, ax, contour in zip([3, 2, 1], axes[:, 0], contours):
    # We're reducing the gridsize to more closely match a traditional
    # hand-contouring grid, similar to Kamb's original work and Vollmer's
    # Figure 5. `gridsize=10` produces a 10x10 grid of density estimates.
    plot(ax, strike, dip, rake, method='kamb', sigma=sigma,
        levels=contour, gridsize=10)

# Kamb contouring with inverse-linear smoothing (after Vollmer, 1995)
for sigma, ax, contour in zip([3, 2, 1], axes[:, 1], contours):
    plot(ax, strike, dip, rake, method='linear_kamb', sigma=sigma,
        levels=contour)
    template = r'$E={}\sigma$ Contours: ${}\sigma,{}\sigma,\ldots$'
    ax.set_xlabel(template.format(sigma, *contour[:2]))

# Kamb contouring with exponential smoothing (after Vollmer, 1995)
for sigma, ax, contour in zip([3, 2, 1], axes[:, 2], contours):
    plot(ax, strike, dip, rake, method='exponential_kamb', sigma=sigma,
        levels=contour)

# Title the different methods
methods = ['Kamb', 'Linear\nSmoothing', 'Exponential\nSmoothing']
for ax, title in zip(axes[0, :], methods):
    ax.set_title(title)

# Hide top-right axis... (Need to implement Diggle & Fisher's method)
axes[0, -1].set_visible(False)

# Schmidt contouring (a.k.a. 1%)
plot(axes[1, -1], strike, dip, rake, method='schmidt', gridsize=25,
     levels=range(3, 20, 3))
axes[1, -1].set_title('Schmidt')
axes[1, -1].set_xlabel(r'Contours: $3\%,6\%,\\ldots$')

# Raw data.
axes[-1, -1].set_azimuth_ticks([])
axes[-1, -1].rake(strike, dip, rake, 'ko', markersize=2)
axes[-1, -1].set_xlabel('N={}'.format(len(strike)))

plt.show()

```

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

### circmean

Source: https://mplstereonet.readthedocs.io/en/latest/_modules/mplstereonet/utilities.html

None

```python
def circmean(azimuths):
    azimuths = np.radians(azimuths)
    x = np.cos(azimuths)
    y = np.sin(azimuths)
    return np.degrees(np.arctan2(y.mean(), x.mean()))
```

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

### Plot density contours of poles to planes with contours at [1,2,3] standard deviations.

Source: https://mplstereonet.readthedocs.io/en/latest/_modules/mplstereonet/stereonet_axes.html

This example demonstrates plotting density contours with specified levels for standard deviations.

```python
strikes, dips = [120, 315, 86], [22, 85, 31]
ax.density_contour(strikes, dips, levels=[1,2,3])
```

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

### Stereonet Explanation

Source: https://mplstereonet.readthedocs.io/en/latest/examples/stereonet_explanation.html

This example illustrates the difference between the internal coordinate system of longitude and latitude and the conceptual coordinate system of a lower-hemisphere stereonet. It sets up a figure with two axes, one for the stereonet projection and one for the native projection, and explains how azimuth and dip relate to longitude and latitude.

```python
import matplotlib.pyplot as plt
import numpy as np
import mplstereonet

def main():
    fig, (ax1, ax2) = setup_figure()
    stereonet_projection_explanation(ax1)
    native_projection_explanation(ax2)
    plt.show()

def setup_figure():
    """Setup the figure and axes"""
    fig, axes = mplstereonet.subplots(ncols=2, figsize=(20,10))
    for ax in axes:
        # Make the grid lines solid.
        ax.grid(ls='-')
        # Make the longitude grids continue all the way to the poles
        ax.set_longitude_grid_ends(90)
    return fig, axes

def stereonet_projection_explanation(ax):
    """Example to explain azimuth and dip on a lower-hemisphere stereonet."""
    ax.set_title('Dip and Azimuth', y=1.1, size=18)

    # Set the azimuth ticks to be just "N", "E", etc.
    ax.set_azimuth_ticks(range(0, 360, 10))

    # Hackishly set some of the azimuth labels to North, East, etc...
    fmt = ax.yaxis.get_major_formatter()
    labels = [fmt(item) for item in ax.get_azimuth_ticks()]
    labels[0] = 'North'
    labels[9] = 'East'
    labels[18] = 'South'
    labels[27] = 'West'
    ax.set_azimuth_ticklabels(labels)

    # Unhide the xticklabels and use them for dip labels
    ax.xaxis.set_tick_params(label1On=True)
    labels = list(range(10, 100, 10)) + list(range(80, 0, -10))
    ax.set_xticks(np.radians(np.arange(-80, 90, 10)))
    ax.set_xticklabels([fmt(np.radians(item)) for item in labels])

    ax.set_xlabel('Dip or Plunge')

    xlabel_halo(ax)
    return ax

def native_projection_explanation(ax):
    """Example showing how the "native" longitude and latitude relate to the
    stereonet projection."""
    ax.set_title('Longitude and Latitude', size=18, y=1.1)

    # Hide the azimuth labels
    ax.set_azimuth_ticklabels([])

    # Make the axis tick labels visible:
    ax.set_xticks(np.radians(np.arange(-80, 90, 10)))
    ax.tick_params(label1On=True)

    ax.set_xlabel('Longitude')

    xlabel_halo(ax)
    return ax

def xlabel_halo(ax):
    """Add a white "halo" around the xlabels."""
    import matplotlib.patheffects as effects
    for tick in ax.get_xticklabels() + [ax.xaxis.label]:
        tick.set_path_effects([effects.withStroke(linewidth=4, foreground='w')])

if __name__ == '__main__':
    main()

```

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

### Plot density contours of a set of "raw" longitudes and latitudes.

Source: https://mplstereonet.readthedocs.io/en/latest/_modules/mplstereonet/stereonet_axes.html

This example demonstrates plotting density contours for raw longitude and latitude measurements.

```python
lon, lat = np.radians([-40, 30, -85]), np.radians([21, -59, 45])
ax.density_contour(lon, lat, measurement='radians')
```
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