Source code for openquake.hmtk.strain.geodetic_strain

# -*- coding: utf-8 -*-
# vim: tabstop=4 shiftwidth=4 softtabstop=4

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# LICENSE
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# Copyright (c) 2010-2017, GEM Foundation, G. Weatherill, M. Pagani,
# D. Monelli.
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# The Hazard Modeller's Toolkit is free software: you can redistribute
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# Earthquake Model).
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'''
:class:`openquake.hmtk.strain.geodectic_strain.GeodeticStain` is a
core class for storage and implementation of a geodetic strain rate
model
'''
import numpy as np
from copy import deepcopy

DATA_VARIABLES = ['longitude', 'latitude', 'exx', 'eyy', 'exy']


class GeodeticStrain(object):
    '''
    :class:`openquake.hmtk.strain.geodetic_strain.GeodeticStrain` describes
    the geodetic strain model

    :param dict data:
        Strain data in the form of a dictionary where is vector of attributes
        is stored under the correponding dictionary key (i.e.
        - longitude - Longitude of point
        - latitude - Latitiude of point
        - exx - xx-component of strain tensor
        - eyy - yy-component of strain tensor
        - exy - xy-component of strain tensor
    :param numpy.ndarray seismicity_rate:
        Seismicity rate at each point associated with the strain model
    :param numpy.ndarray target_magnitudes:
        Magnitudes for the corresponding activity rates
    :param list data_variables:
        List of strain data attributes in the current class
    '''

    def __init__(self):
        '''Instantiates'''
        self.data = None
        self.regions = None
        self.seismicity_rate = None
        self.regionalisation = None
        self.target_magnitudes = None
        self.data_variables = []

    def get_secondary_strain_data(self, strain_data=None):
        '''
        Calculate the following and add to data dictionary:
        1) 2nd invarient of strain
        2) Dilatation rate
        3) e1h and e2h
        4) err

        :param dict strain_data:
            Strain data dictionary (as described) - will overwrite current
            data if input

        '''
        if strain_data:
            self.data = strain_data

        if not isinstance(self.data, dict):
            raise ValueError('Strain data not input or incorrectly formatted')

        # Check to ensure essential attributes are in data dictionary
        for essential_key in DATA_VARIABLES:
            if essential_key not in self.data:
                print(self.data)
                raise ValueError('Essential strain information %s missing!'
                                 % essential_key)
        self.data_variables = deepcopy(DATA_VARIABLES)

        # Second Invarient
        self.data['2nd_inv'] = np.sqrt(
            (self.data['exx'] ** 2.) +
            (self.data['eyy'] ** 2.) +
            2.0 * (self.data['exy'] ** 2.))
        # Dilatation
        self.data['dilatation'] = self.data['exx'] + self.data['eyy']
        # err
        self.data['err'] = -1. * self.data['dilatation']
        center_normal_rate = (self.data['exx'] +
                              self.data['eyy']) / 2.
        radius_rate = np.sqrt((self.data['exx'] -
                               center_normal_rate) ** 2. +
                              (self.data['exy'] ** 2.))
        # e1h and e2h
        self.data['e1h'] = center_normal_rate - radius_rate
        self.data['e2h'] = center_normal_rate + radius_rate
        self.data['area'] = np.zeros(self.get_number_observations())
        self.data_variables.extend(['2nd_inv', 'dilatation', 'err', 'e1h',
                                    'e2h'])

    def get_number_observations(self):
        '''
        Returns the number of observations in the data file
        '''
        if isinstance(self.data, dict) and ('exx' in self.data.keys()):
            return len(self.data['exx'])
        else:
            return 0