Skip to content

shock.py

ChangepointMethods 


              flowchart TD
              erosionfront.levelset.shock.ChangepointMethods[ChangepointMethods]

              

              click erosionfront.levelset.shock.ChangepointMethods href "" "erosionfront.levelset.shock.ChangepointMethods"

ruptures package changepoint method choices.

Returned by: Used by:

choose_changepoint_method 

choose_changepoint_method(method: str = 'Binseg') -> ChangepointMethods

ruptures package changepoint method selector.

Parameters

method: str="Binseg" One of "Pelt", "Window", "Binseg".

Returns

ChangepointMethods: One of the enumerated set of methods: PELT, WINDOW, BINSEG.

Source code in erosionfront/levelset/shock.py 
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
def choose_changepoint_method(method: str="Binseg",) -> ChangepointMethods:
    """
    `ruptures` package changepoint method selector.

    Parameters
    ----------
    method: str="Binseg"
        One of "Pelt", "Window", "Binseg".

    Returns
    -------
    ChangepointMethods:
        One of the enumerated set of methods: `PELT`, `WINDOW`, `BINSEG`.
    """
    match method:
        case ChangepointMethods.PELT:
            return ChangepointMethods.PELT
        case ChangepointMethods.WINDOW:
            return ChangepointMethods.WINDOW
        case _: #ChangepointMethods.BINSEG:
            return ChangepointMethods.BINSEG

ShocksMixin

Mixin providing shock (break-in-slope) detection methods.

Parameters

T_slices: dict All the time-sliced surfaces (x,z coordinate arrays).

Methods:

  • find_shock –

    Locate main break-in-slope by smoothing & changepoint detection.

  • find_shocks –

    Find breaks-in-slope in the set of T-sliced surfaces.

find_shock 

find_shock(
    i_step: int,
    method: ChangepointMethods = BINSEG,
    i_max: int = 300,
    n_filterwidth: int = 50,
    which_changepoint: int = 1,
    do_plot: bool = False,
) -> tuple[float, float]

Locate main break-in-slope by smoothing & changepoint detection.

Parameters

i_step: int

method: ChangepointMethods=ChangepointMethods.BINSEG

i_max: int=300

n_filterwidth: int=50

which_changepoint: int=1

do_plot: bool=False

Returns

tuple[float, float]: x, z coordinate of break-in-slope shock changepoint.

Source code in erosionfront/levelset/shock.py 
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
def find_shock(
        self, 
        i_step: int, 
        method: ChangepointMethods=ChangepointMethods.BINSEG,
        i_max: int=300,
        n_filterwidth: int=50,
        which_changepoint: int=1,
        do_plot: bool=False, 
    ) -> tuple[float, float]:
    """
    Locate main break-in-slope by smoothing & changepoint detection.

    Parameters
    ----------
    i_step: int

    method: ChangepointMethods=ChangepointMethods.BINSEG

    i_max: int=300

    n_filterwidth: int=50

    which_changepoint: int=1

    do_plot: bool=False

    Returns
    -------
    tuple[float, float]:
        x, z coordinate of break-in-slope shock changepoint.
    """
    changepoint_fn: ruptures.Pelt | ruptures.Window | ruptures.Binseg
    changepoints: list
    β_max: float = np.pi/2 * 0.95
    β_: NDArray = median_filter(self.T_slices[i_step]["β"], n_filterwidth,)
    i_β_cliff: NDArray = np.where(β_>β_max)[0]
    i_end: int = max(
        i_β_cliff[0] if i_β_cliff.shape[0]>1
        else len(β_), i_max
    )
    β_ = β_[:i_end]
    match method:
        case ChangepointMethods.PELT: 
            changepoint_fn = ruptures.Pelt(model="l2", min_size=30,)
            changepoint_fn.fit(β_)
            changepoints = changepoint_fn.predict(pen=3,)
        case ChangepointMethods.WINDOW:
            changepoint_fn = ruptures.Window(model="l2", width=10,)
            changepoint_fn.fit(β_)
            changepoints = changepoint_fn.predict(n_bkps=2,)
        case ChangepointMethods.BINSEG:
            changepoint_fn = ruptures.Binseg(model="l2", min_size=10,)
            changepoint_fn.fit(β_)
            changepoints = changepoint_fn.predict(n_bkps=2,)
    i_shock: int = changepoints[which_changepoint]
    if do_plot:
        ruptures.display(β_, [], changepoints)
    return (
        self.T_slices[i_step]["x"][i_shock], 
        self.T_slices[i_step]["z"][i_shock],
    )

find_shocks 

find_shocks(
    method: ChangepointMethods = BINSEG,
    subset: slice = s_[100:1000:50],
    i_max: int = 1000,
    n_filterwidth: int = 50,
    which_changepoint=0,
    i_plot: int = 200,
    i_plot_offset: int = 50,
) -> None

Find breaks-in-slope in the set of T-sliced surfaces.

Parameters

method: ChangepointMethods=ChangepointMethods.BINSEG

subset: slice=np.s_[100:1000:50]

i_max: int=1000

n_filterwidth: int=50

which_changepoint=0,

i_plot: int=200

i_plot_offset: int=50

Attributes

Modifies shocks_xz with estimated locations of breaks-in-slope.

Source code in erosionfront/levelset/shock.py 
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
def find_shocks(
        self,
        method: ChangepointMethods=ChangepointMethods.BINSEG,
        subset: slice=np.s_[100:1000:50],
        i_max: int=1000,
        n_filterwidth: int=50,
        which_changepoint=0,
        i_plot: int=200,
        i_plot_offset: int=50,
    ) -> None:
    """
    Find breaks-in-slope in the set of T-sliced surfaces.

    Parameters
    ----------
    method: ChangepointMethods=ChangepointMethods.BINSEG

    subset: slice=np.s_[100:1000:50]

    i_max: int=1000

    n_filterwidth: int=50

    which_changepoint=0,

    i_plot: int=200

    i_plot_offset: int=50

    Attributes
    ----------
    Modifies `shocks_xz` with estimated locations of breaks-in-slope.
    """
    slices: list = list(self.T_slices.keys())[subset]
    self.shocks_xz: NDArray = np.array([
        self.find_shock(
            i_step_, 
            method=method,
            i_max=i_max,
            n_filterwidth=n_filterwidth,
            which_changepoint=which_changepoint,
            do_plot=(
                (i_step_==slices[-1]) | (i_step_-i_plot_offset)%i_plot==0
            ), 
        )
        for i_step_ in slices
    ]).T