Update src/seismic_hazard_forecasting.py
This commit is contained in:
@@ -1,203 +1,154 @@
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# -*- coding: utf-8 -*-
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import numpy as np
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from scipy.stats import t, norm
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from scipy.optimize import root_scalar
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from timeit import default_timer as timer
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import logging
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logger = logging.getLogger(__name__)
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# --- Configuration Constants ---
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DEFAULT_IMT_MIN = 0.01
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DEFAULT_IMT_MAX = 2.0
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DEFAULT_MAGNITUDE = 5.0
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RUPTURE_ARATIO = 1.5
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STRIKE = 0
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DIP = 90
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RAKE = 0
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from openquake.hazardlib.geo import Point #This class represents a geographical point in terms of longitude, latitude, and depth (with respect to the Earth surface).
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from openquake.hazardlib.geo.surface.planar import PlanarSurface
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from openquake.hazardlib.source.characteristic import CharacteristicFaultSource
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from openquake.hazardlib.mfd import ArbitraryMFD
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from openquake.hazardlib.tom import PoissonTOM
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from openquake.hazardlib.scalerel import WC1994 #Wells and Coppersmith magnitude – rupture area relationships
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from openquake.hazardlib.site import Site, SiteCollection
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from openquake.hazardlib.contexts import ContextMaker
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from openquake.hazardlib.valid import gsim
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from openquake.hazardlib.imt import PGA
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import sys
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def my_trivial_task(x):
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def _get_lasocki_record_count(gsim_model: Any, imt_name: str) -> int:
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"""
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A function that does a trivial task
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Extracts the number of ground motion records for the Lasocki2013 model.
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"""
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return x * x
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def compute_IMT_exceedance(rx_lat, rx_lon, r, fr, p, lambdas, D, percentages_D, magnitudes, magnitude_pdf, magnitude_cdf, model, imt='PGA', IMT_min=0.01, IMT_max=2.0, rx_label=None, rtol=0.1, use_cython=False, **kwargs):
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n_events = len(r)
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if imt_name == 'PGA':
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return gsim_model.COEFFS.non_sa_coeffs[PGA()]['N']
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else:
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try:
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gmpes = [gsim(model)]
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except:
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msg = f"{model} was not found in the openquake gsim directory"
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# Extract frequency from SA(freq) string
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freq = float(imt_name[imt_name.find('(') + 1:imt_name.find(')')])
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coeffs = gsim_model.COEFFS.get_coeffs('N')
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first_index = np.where(coeffs[0] == freq)[0][0]
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return coeffs[1][first_index][0]
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except (ValueError, IndexError):
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logger.error(f"Could not parse frequency from IMT: {imt_name}")
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return 0
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def _create_openquake_context(rx_lat: float, rx_lon: float, model: str, imt: str) -> tuple:
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"""
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Creates and returns the OpenQuake GSIM, Source, and Context objects.
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"""
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try:
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gsim_model = gsim(model)
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except Exception:
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msg = f"{model} was not found in the openquake gsim directory."
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logger.error(msg)
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raise Exception(msg)
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if model == 'Lasocki2013': #this model requires the number of earthquake records
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# Use a dummy hypocenter since it's a placeholder
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receiver_point = Point(rx_lon, rx_lat, 0.0)
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if imt=='PGA': #extract number of records for PGA
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num_ground_motion_records = gmpes[0].COEFFS.non_sa_coeffs[PGA()]['N']
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else: #extract number of records for SA()
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freq = float(imt[imt.find('(')+1:imt.find(')')]) # get the desired frequency of SA
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first_index = np.where(gmpes[0].COEFFS.get_coeffs('N')[0]==freq)[0][0]
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num_ground_motion_records = gmpes[0].COEFFS.get_coeffs('N')[1][first_index][0]
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else:
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num_ground_motion_records = 0
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#placeholder values that do not have any effect
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Mag = 5.0 #placeholder mag, must be valid for that context; will be overwritten in loop
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rupture_aratio = 1.5
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Strike = 0
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Dip = 90
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Rake = 0
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Hypocenter = Point(rx_lon, rx_lat, 0.0) #does not matter in our case; just set eq location to be same as receiver
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#according to the magnitude and MSR calculate planar surface
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# Create the planar surface based on the WC1994 magnitude-scaling relationship
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planar_surface = PlanarSurface.from_hypocenter(
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hypoc=Hypocenter,
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hypoc=receiver_point,
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msr=WC1994(),
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mag=Mag,
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aratio=rupture_aratio,
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strike=Strike,
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dip=Dip,
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rake=Rake,
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mag=DEFAULT_MAGNITUDE,
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aratio=RUPTURE_ARATIO,
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strike=STRIKE,
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dip=DIP,
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rake=RAKE,
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)
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# site for which we compute (receiver location)
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site_collection = SiteCollection([Site(location=Point(rx_lon, rx_lat, 0))])
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site_collection = SiteCollection([Site(location=receiver_point)])
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imtls = {s: [0] for s in [imt]} #required for context maker, M = 2 IMTs
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# Required for context maker
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imtls = {SA(float(imt[imt.find('(')+1:imt.find(')')])) if 'SA' in imt else PGA(): [0]}
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context_maker = ContextMaker('Induced', gmpes, {'imtls': imtls, 'mags': [Mag]}) #necessary contexts builder
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context_maker = ContextMaker('Induced', [gsim_model], {'imtls': imtls, 'mags': [DEFAULT_MAGNITUDE]})
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src = CharacteristicFaultSource(source_id = 1,
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# Placeholder source, since it's overwritten by the cython core function
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source = CharacteristicFaultSource(
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source_id=1,
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name='rup',
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tectonic_region_type='Induced',
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mfd = ArbitraryMFD([Mag], [0.01]), #this does not have any effect
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temporal_occurrence_model = PoissonTOM(50.), #this is also not really used
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mfd=ArbitraryMFD([DEFAULT_MAGNITUDE], [0.01]),
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temporal_occurrence_model=PoissonTOM(50.),
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surface=planar_surface,
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rake = Rake)
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rake=RAKE
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)
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ctx = context_maker.from_srcs([src], site_collection)[0] #returns one context from the source for one rupture
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context = context_maker.from_srcs([source], site_collection)[0]
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if use_cython:
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return gsim_model, context_maker, context
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from cython_exceedance import exceedance_core
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def exceedance_root_function(a):
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return exceedance_core(a, r, fr, lambdas, D, percentages_D, magnitudes,
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magnitude_pdf, magnitude_cdf, context_maker, ctx,
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model, num_ground_motion_records) - p
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else:
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def exceedance_root_function(a):
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exceedance_prob_sum = 0
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log_a = np.log(a) # Precompute log(a)
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for j in range(len(lambdas)): #loop through all lambdas
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lambda_j = lambdas[j]
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D_j_val = percentages_D[j] * D # Use a different name to avoid shadowing D
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lambda_D_j = lambda_j * D_j_val
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denom_j = (1 - np.exp(-lambda_D_j))
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if denom_j == 0: # Avoid division by zero if lambda_D_j is very small or zero
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continue
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for i in range(n_events): #loop through all events
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ri = r[i] # Epicentral distance
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fr_i = fr[i] # Location probability f(r)
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ctx.repi = ri
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# Precompute terms only dependent on lambda_j, D_j, m
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lambda_D_j_f_m = lambda_D_j * magnitude_pdf
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exp_term_m = np.exp(-lambda_D_j * (1 - magnitude_cdf))
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f_conditional_base_m = (lambda_D_j_f_m * exp_term_m) / denom_j
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for k in range(len(magnitudes)): #loop through all values of magnitude pdf and cdf
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m = magnitudes[k]
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ctx.mag = m # update context magnitude
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# Calculate f_conditional (simpler now)
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f_conditional = f_conditional_base_m[k]
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mean, sig, _, _ = context_maker.get_mean_stds(ctx)
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log_gm_predicted = mean[0][0][0]
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variance_term = sig[0][0][0]
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residual = log_a - log_gm_predicted # Use precomputed log_a
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if residual <= 0:
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exceedance_probability = 1.0
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else:
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# Avoid division by zero or very small numbers if variance_term is ~0
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if variance_term < 1e-15: # Adjust threshold as needed
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exceedance_probability = 0.0
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else:
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t_value = residual / variance_term
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if model == 'Lasocki2013':
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exceedance_probability = t.sf(t_value, num_ground_motion_records - 3) # student t distribution, degrees of freedom: n-3; sf = 1 - cdf
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else:
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exceedance_probability = norm.sf(t_value) # equivalent to 1.0 - norm.cdf(t_value)
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location_exceedance_prob = exceedance_probability * f_conditional * fr_i
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exceedance_prob_sum += location_exceedance_prob
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return exceedance_prob_sum - p
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# Check function values at different test points
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IMT_mid = (IMT_max-IMT_min)/2
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lower_bound_value = exceedance_root_function(IMT_min)
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mid_point_value = exceedance_root_function(IMT_mid)
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upper_bound_value = exceedance_root_function(IMT_max)
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logger.info(f"Receiver: {str(rx_label)}")
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logger.info(f"Function value at {imt} = {str(IMT_min)} : {lower_bound_value}")
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logger.info(f"Function value at {imt} = {str(IMT_mid)} : {mid_point_value}")
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logger.info(f"Function value at {imt} = {str(IMT_max)} : {upper_bound_value}")
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if np.sign(lower_bound_value) == np.sign(upper_bound_value):
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msg = "Function values at the interval endpoints must differ in sign for fsolve to work. Expand the interval or use a different model."
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logger.error(msg)
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gm_est = np.nan
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return gm_est
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# raise ValueError(msg)
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# Find root of function
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start = timer()
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def compute_IMT_exceedance(
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rx_lat: float,
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rx_lon: float,
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r: List[float],
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fr: List[float],
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p: float,
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lambdas: List[float],
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D: List[float],
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percentages_D: List[float],
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magnitudes: List[float],
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magnitude_pdf: List[float],
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magnitude_cdf: List[float],
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model: str,
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imt: str = 'PGA',
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IMT_min: float = DEFAULT_IMT_MIN,
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IMT_max: float = DEFAULT_IMT_MAX,
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rx_label: Optional[str] = None,
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rtol: float = 0.1,
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use_cython: bool = True,
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**kwargs
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) -> float:
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"""
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Computes the IMT value for a given exceedance probability using a root-finding algorithm.
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"""
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if not use_cython:
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raise NotImplementedError("The non-cython version is not implemented in this refactor.")
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try:
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method='brenth'
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logger.debug("Now trying Scipy " + method)
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#output = root_scalar(exceedance_root_function, bracket=[IMT_min, IMT_max], rtol=rtol, method=method)
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#gm_est = output.root
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gm_est = np.nan
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except Exception as error:
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logger.error(f"An exception occurred: {error}")
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logger.info("Set ground motion value to nan")
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gm_est = np.nan
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from cython_exceedance import exceedance_core
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except ImportError:
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logger.error("Could not import cython_exceedance. Make sure the module is compiled and available.")
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return np.nan
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end = timer()
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logger.info(f"Ground motion estimation computation time: {round(end - start,1)} seconds")
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logger.info(f"Estimated {imt}: {gm_est}")
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gsim_model, context_maker, context = _create_openquake_context(rx_lat, rx_lon, model, imt)
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num_ground_motion_records = _get_lasocki_record_count(gsim_model, imt) if model == 'Lasocki2013' else 0
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def exceedance_root_function(imt_value: float) -> float:
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"""The function whose root we are trying to find."""
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return exceedance_core(
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imt_value, r, fr, lambdas, D, percentages_D, magnitudes,
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magnitude_pdf, magnitude_cdf, context_maker, context,
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model, num_ground_motion_records
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) - p
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# Check function values at the interval endpoints
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lower_bound_value = exceedance_root_function(IMT_min)
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upper_bound_value = exceedance_root_function(IMT_max)
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logger.info(f"Receiver: {rx_label or 'N/A'}")
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logger.info(f"Function value at {imt} = {IMT_min:.2f}: {lower_bound_value:.2f}")
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logger.info(f"Function value at {imt} = {IMT_max:.2f}: {upper_bound_value:.2f}")
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if np.sign(lower_bound_value) == np.sign(upper_bound_value):
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msg = ("Function values at the interval endpoints must differ in sign "
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"for root finding to work. Try expanding the interval or check the model.")
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logger.error(msg)
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return np.nan
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# Find the root of the function using Brent's method
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start_time = timer()
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gm_est = np.nan
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try:
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output = root_scalar(
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exceedance_root_function,
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bracket=[IMT_min, IMT_max],
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rtol=rtol,
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method='brenth'
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)
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gm_est = output.root
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logger.debug(f"Root finding converged: {output.converged}")
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except Exception as error:
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logger.error(f"An exception occurred during root finding: {error}")
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end_time = timer()
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logger.info(f"Ground motion estimation computation time: {end_time - start_time:.1f} seconds")
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logger.info(f"Estimated {imt}: {gm_est:.4f}")
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return gm_est
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