# Source code for openquake.hazardlib.mfd.arbitrary_mfd

```
# The Hazard Library
# Copyright (C) 2016-2018 GEM Foundation
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
Module :mod:`openquake.hazardlib.mfd.evenly_discretized` defines an evenly
discretized MFD.
"""
from openquake.hazardlib.mfd.base import BaseMFD
from openquake.baselib.slots import with_slots
[docs]@with_slots
class ArbitraryMFD(BaseMFD):
"""
An arbitrary MFD is defined as a list of tuples of magnitude values and
their corresponding rates
:param magnitudes:
List of magnitudes
:param occurrence_rates:
The list of non-negative float values representing the actual
annual occurrence rates. The resulting histogram has as many bins
as this list length.
"""
MODIFICATIONS = set(('set_mfd',))
_slots_ = 'magnitudes occurrence_rates'.split()
def __init__(self, magnitudes, occurrence_rates):
self.magnitudes = magnitudes
self.occurrence_rates = occurrence_rates
self.check_constraints()
[docs] def check_constraints(self):
"""
Checks the following constraints:
* Magnitude list and occurrence rate lists are the same length
* Occurrence rates list is not empty.
* Each number in occurrence rates list is non-negative.
* Minimum magnitude is positive.
"""
if not len(self.occurrence_rates):
raise ValueError('at least one bin must be specified')
if not all(value >= 0 for value in self.occurrence_rates):
raise ValueError('all occurrence rates must not be negative')
if not any(value > 0 for value in self.occurrence_rates):
raise ValueError('at least one occurrence rate must be positive')
if not len(self.magnitudes) == len(self.occurrence_rates):
raise ValueError(
'lists of magnitudes and rates must have same length')
[docs] def get_annual_occurrence_rates(self):
"""
Returns the predefined annual occurrence rates.
"""
return list(zip(self.magnitudes, self.occurrence_rates))
[docs] def get_min_max_mag(self):
"""
Returns the minumun and maximum magnitudes
"""
return min(self.magnitudes), max(self.magnitudes)
[docs] def modify_set_mfd(self, magnitudes, occurrence_rates):
"""
Applies absolute modification of the MFD from the ``magnitudes``,
``occurrence_rates`` modification.
:param magnitudes:
List of magnitudes
:param occurrence_rates:
The list of non-negative float values representing the actual
annual occurrence rates. The resulting histogram has as many bins
as this list length.
"""
self.magnitudes = magnitudes
self.occurrence_rates = occurrence_rates
self.check_constraints()
```