Source code for openquake.risklib.utils

# -*- coding: utf-8 -*-
# vim: tabstop=4 shiftwidth=4 softtabstop=4
#
# Copyright (C) 2010-2017 GEM Foundation
#
# OpenQuake 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.
#
# OpenQuake 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 OpenQuake. If not, see <http://www.gnu.org/licenses/>.

import itertools
import numpy
from decorator import decorate


# copied from https://github.com/micheles/decorator/blob/master/docs/tests.documentation.rst
def _memoize(func, *args, **kw):
    if kw:  # frozenset is used to ensure hashability
        key = args, frozenset(kw.items())
    else:
        key = args
    cache = func.cache  # attribute added by memoize
    if key not in cache:
        cache[key] = func(*args, **kw)
    return cache[key]


def memoized(func):
    """
    A simple memoize implementation. It works by adding a .cache dictionary
    to the decorated function. The cache will grow indefinitely, so it is
    your responsibility to clear it, if needed.
    """
    func.cache = {}
    return decorate(func, _memoize)


def pairwise(iterable):
    "s -> (s0,s1), (s1,s2), (s2, s3), ..."
    a, b = itertools.tee(iterable)
    # b ahead one step; if b is empty do not raise StopIteration
    next(b, None)
    return zip(a, b)  # if a is empty will return an empty iter


def numpy_map(f, *args):
    return numpy.array(list(map(f, *args)))