utils.py 文件源码

def set_matplotlib_backend(backend=None, batch=None, silent=True):
    """Set Matplotlib backend

    :param str backend: backend to set
    :param bool batch: require backend to be non-interactive
    :param bool silent: do not raise exception if backend cannot be set
    :raises: RuntimeError
    """

    # determine if batch mode is required
    display = get_env_var('display')
    run_batch = bool(batch) or display is None or not display.startswith(':') or not display[1].isdigit()
    if run_batch:
        matplotlib.interactive(False)

    # check if batch mode can be set if it is requested
    if not batch and batch is not None and run_batch:
        if not silent:
            raise RuntimeError('interactive Matplotlib mode requested, but no display found')
        log.warning('Matplotlib cannot be used interactively; no display found')

    # get Matplotlib backends
    curr_backend = matplotlib.get_backend().lower()
    ni_backends = [nib.lower() for nib in matplotlib.rcsetup.non_interactive_bk]

    # determine backend to be set
    if not backend:
        # try to use current backend
        backend = curr_backend if not run_batch or curr_backend in ni_backends else ni_backends[0]
    backend = str(backend).lower()

    # check if backend is compatible with mode
    if run_batch and backend not in ni_backends:
        if not silent:
            raise RuntimeError('non-interactive Matplotlib backend required, but "{}" requested'.format(str(backend)))
        log.warning('Set Matplotlib backend to "%s"; non-interactive backend required, but "%s" requested',
                    ni_backends[0], backend)
        backend = ni_backends[0]

    # check if backend has to change
    if backend == curr_backend:
        return

    # check if backend can still be set
    if 'matplotlib.pyplot' in sys.modules:
        if not silent:
            raise RuntimeError('cannot set Matplotlib backend: pyplot module already loaded')
        return

    # set backend
    matplotlib.use(backend)