ipython_directive.py 文件源码

def ensure_pyplot(self):
        """
        Ensures that pyplot has been imported into the embedded IPython shell.

        Also, makes sure to set the backend appropriately if not set already.

        """
        # We are here if the @figure pseudo decorator was used. Thus, it's
        # possible that we could be here even if python_mplbackend were set to
        # `None`. That's also strange and perhaps worthy of raising an
        # exception, but for now, we just set the backend to 'agg'.

        if not self._pyplot_imported:
            if 'matplotlib.backends' not in sys.modules:
                # Then ipython_matplotlib was set to None but there was a
                # call to the @figure decorator (and ipython_execlines did
                # not set a backend).
                #raise Exception("No backend was set, but @figure was used!")
                import matplotlib
                matplotlib.use('agg')

            # Always import pyplot into embedded shell.
            self.process_input_line('import matplotlib.pyplot as plt',
                                    store_history=False)
            self._pyplot_imported = True