qiskit/providers/providerutils.py
def filter_backends(backends, filters=None, **kwargs):
    """Return the backends matching the specified filtering.

    Filter the `backends` list by their `configuration` or `status`
    attributes, or from a boolean callable. The criteria for filtering can
    be specified via `**kwargs` or as a callable via `filters`, and the
    backends must fulfill all specified conditions.

    Args:
        backends (list[BaseBackend]): list of backends.
        filters (callable): filtering conditions as a callable.
        **kwargs (dict): dict of criteria.

    Returns:
        list[BaseBackend]: a list of backend instances matching the
            conditions.
    """
    def _match_all(obj, criteria):
        """Return True if all items in criteria matches items in obj."""
        return all(getattr(obj, key_, None) == value_ for
                   key_, value_ in criteria.items())

    # Inspect the backends to decide which filters belong to
    # backend.configuration and which ones to backend.status, as it does
    # not involve querying the API.
    configuration_filters = {}
    status_filters = {}
    for key, value in kwargs.items():
        if all(key in backend.configuration() for backend in backends):
            configuration_filters[key] = value
        else:
            status_filters[key] = value

    # 1. Apply backend.configuration filtering.
    if configuration_filters:
        backends = [b for b in backends if
                    _match_all(b.configuration(), configuration_filters)]

    # 2. Apply backend.status filtering (it involves one API call for
    # each backend).
    if status_filters:
        backends = [b for b in backends if
                    _match_all(b.status(), status_filters)]

    # 3. Apply acceptor filter.
    backends = list(filter(filters, backends))

    return backends
def filter_backends(backends, filters=None, **kwargs):
    """Return the backends matching the specified filtering.

    Filter the `backends` list by their `configuration` or `status`
    attributes, or from a boolean callable. The criteria for filtering can
    be specified via `**kwargs` or as a callable via `filters`, and the
    backends must fulfill all specified conditions.

    Args:
        backends (list[BaseBackend]): list of backends.
        filters (callable): filtering conditions as a callable.
        **kwargs (dict): dict of criteria.

    Returns:
        list[BaseBackend]: a list of backend instances matching the
            conditions.
    """
    def _match_all(obj, criteria):
        """Return True if all items in criteria matches items in obj."""
        return all(getattr(obj, key_, None) == value_ for
                   key_, value_ in criteria.items())

    # Inspect the backends to decide which filters belong to
    # backend.configuration and which ones to backend.status, as it does
    # not involve querying the API.
    configuration_filters = {}
    status_filters = {}
    for key, value in kwargs.items():
        if all(key in backend.configuration() for backend in backends):
            configuration_filters[key] = value
        else:
            status_filters[key] = value

    # 1. Apply backend.configuration filtering.
    if configuration_filters:
        backends = [b for b in backends if
                    _match_all(b.configuration(), configuration_filters)]

    # 2. Apply backend.status filtering (it involves one API call for
    # each backend).
    if status_filters:
        backends = [b for b in backends if
                    _match_all(b.status(), status_filters)]

    # 3. Apply acceptor filter.
    backends = list(filter(filters, backends))

    return backends
Return the backends matching the specified filtering.

    Filter the `backends` list by their `configuration` or `status`
    attributes, or from a boolean callable. The criteria for filtering can
    be specified via `**kwargs` or as a callable via `filters`, and the
    backends must fulfill all specified conditions.

    Args:
        backends (list[BaseBackend]): list of backends.
        filters (callable): filtering conditions as a callable.
        **kwargs (dict): dict of criteria.

    Returns:
        list[BaseBackend]: a list of backend instances matching the
            conditions.