Add support for simultaneous interactive and inline matplotlib plots.

In purely svg mode, there is now no lag with draw() operations, they
just produce the figure immediately.

And in gui mode, a new function, 'paste', is added to plt and to the
user's namespace, that pastes open figures from GUI windows into the
editing widget as inline SVGs.

IPython/core/interactiveshell.py

@@ -162,6 +162,7 b' class InteractiveShell(Configurable, Magic):'
     object_info_string_level = Enum((0,1,2), default_value=0,
                                     config=True)
     pdb = CBool(False, config=True)
+
     pprint = CBool(True, config=True)
     profile = Str('', config=True)
     prompt_in1 = Str('In [\\#]: ', config=True)
@@ -212,6 +213,9 b' class InteractiveShell(Configurable, Magic):'
     plugin_manager = Instance('IPython.core.plugin.PluginManager')
     payload_manager = Instance('IPython.core.payload.PayloadManager')
 
+    # Private interface
+    _post_execute = set()
+
     def __init__(self, config=None, ipython_dir=None,
                  user_ns=None, user_global_ns=None,
                  custom_exceptions=((), None)):
@@ -570,6 +574,13 b' class InteractiveShell(Configurable, Magic):'
 
         setattr(self.hooks,name, dp)
 
+    def register_post_execute(self, func):
+        """Register a function for calling after code execution.
+        """
+        if not callable(func):
+            raise ValueError('argument %s must be callable' % func)
+        self._post_execute.add(func)
+
     #-------------------------------------------------------------------------
     # Things related to the "main" module
     #-------------------------------------------------------------------------
@@ -2268,6 +2279,21 b' class InteractiveShell(Configurable, Magic):'
             outflag = 0
             if softspace(sys.stdout, 0):
                 print
+
+        # Execute any registered post-execution functions.  Here, any errors
+        # are reported only minimally and just on the terminal, because the
+        # main exception channel may be occupied with a user traceback.
+        # FIXME: we need to think this mechanism a little more carefully.
+        for func in self._post_execute:
+            try:
+                func()
+            except:
+                head = '[ ERROR ] Evaluating post_execute function: %s' % func
+                print >> io.Term.cout, head
+                print >> io.Term.cout, self._simple_error()
+                print >> io.Term.cout, 'Removing from post_execute'
+                self._post_execute.remove(func)
+
         # Flush out code object which has been run (and source)
         self.code_to_run = None
         return outflag

IPython/frontend/qt/console/ipythonqt.py

@@ -114,9 +114,6 b' def main():'
         if args.pure:
             kernel_manager.start_kernel(ipython=False)
         elif args.pylab:
-            if args.rich:
-                kernel_manager.start_kernel(pylab='payload-svg')
-            else:
                 kernel_manager.start_kernel(pylab=args.pylab)
         else:
             kernel_manager.start_kernel()
@@ -127,7 +124,7 b' def main():'
     if args.pure:
         kind = 'rich' if args.rich else 'plain'
         widget = FrontendWidget(kind=kind, paging=args.paging)
-    elif args.rich:
+    elif args.rich or args.pylab:
         widget = RichIPythonWidget(paging=args.paging)
     else:
         widget = IPythonWidget(paging=args.paging)

IPython/lib/pylabtools.py

@@ -21,6 +21,15 b' Authors'
 
 from IPython.utils.decorators import flag_calls
 
+# If user specifies a GUI, that dictates the backend, otherwise we read the
+# user's mpl default from the mpl rc structure
+backends = {'tk': 'TkAgg',
+            'gtk': 'GTKAgg',
+            'wx': 'WXAgg',
+            'qt': 'Qt4Agg', # qt3 not supported
+            'qt4': 'Qt4Agg',
+            'payload-svg' : 'module://IPython.zmq.pylab.backend_payload_svg'}
+
 #-----------------------------------------------------------------------------
 # Main classes and functions
 #-----------------------------------------------------------------------------
@@ -42,24 +51,15 b' def find_gui_and_backend(gui=None):'
 
     import matplotlib
 
-    # If user specifies a GUI, that dictates the backend, otherwise we read the
-    # user's mpl default from the mpl rc structure
-    g2b = {'tk': 'TkAgg',
-           'gtk': 'GTKAgg',
-           'wx': 'WXAgg',
-           'qt': 'Qt4Agg', # qt3 not supported
-           'qt4': 'Qt4Agg',
-           'payload-svg' : \
-                  'module://IPython.zmq.pylab.backend_payload_svg'}
-
     if gui:
         # select backend based on requested gui
-        backend = g2b[gui]
+        backend = backends[gui]
     else:
         backend = matplotlib.rcParams['backend']
         # In this case, we need to find what the appropriate gui selection call
         # should be for IPython, so we can activate inputhook accordingly
-        b2g = dict(zip(g2b.values(),g2b.keys()))
+        g2b = backends  # maps gui names to mpl backend names
+        b2g = dict(zip(g2b.values(), g2b.keys()))  # reverse dict
         gui = b2g.get(backend, None)
     return gui, backend
 
@@ -90,7 +90,8 b' def activate_matplotlib(backend):'
     # For this, we wrap it into a decorator which adds a 'called' flag.
     pylab.draw_if_interactive = flag_calls(pylab.draw_if_interactive)
 
-def import_pylab(user_ns, import_all=True):
+
+def import_pylab(user_ns, backend, import_all=True, shell=None):
     """Import the standard pylab symbols into user_ns."""
 
     # Import numpy as np/pyplot as plt are conventions we're trying to
@@ -103,6 +104,17 b' def import_pylab(user_ns, import_all=True):'
           "plt = pyplot\n"
           ) in user_ns
 
+    if shell is not None:
+        # If using our svg payload backend, register the post-execution
+        # function that will pick up the results for display.  This can only be
+        # done with access to the real shell object.
+        if backend == backends['payload-svg']:
+            from IPython.zmq.pylab.backend_payload_svg import flush_svg
+            shell.register_post_execute(flush_svg)
+        else:
+            from IPython.zmq.pylab.backend_payload_svg import paste
+            user_ns['paste'] = paste
+
     if import_all:
         exec("from matplotlib.pylab import *\n"
              "from numpy import *\n") in user_ns
@@ -131,7 +143,7 b' def pylab_activate(user_ns, gui=None, import_all=True):'
     """
     gui, backend = find_gui_and_backend(gui)
     activate_matplotlib(backend)
-    import_pylab(user_ns)
+    import_pylab(user_ns, backend)
 
     print """
 Welcome to pylab, a matplotlib-based Python environment [backend: %s].

IPython/zmq/ipkernel.py

@@ -192,11 +192,12 b' class Kernel(Configurable):'
                 # FIXME: runlines calls the exception handler itself.
                 shell._reply_content = None
 
+                # For now leave this here until we're sure we can stop using it
+                #shell.runlines(code)
+
                 # Experimental: cell mode!  Test more before turning into
                 # default and removing the hacks around runlines.
                 shell.run_cell(code)
-                # For now leave this here until we're sure we can stop using it
-                #shell.runlines(code)
         except:
             status = u'error'
             # FIXME: this code right now isn't being used yet by default,
@@ -210,10 +211,6 b' class Kernel(Configurable):'
             reply_content.update(shell._showtraceback(etype, evalue, tb_list))
         else:
             status = u'ok'
-            reply_content[u'payload'] = shell.payload_manager.read_payload()
-            # Be agressive about clearing the payload because we don't want
-            # it to sit in memory until the next execute_request comes in.
-            shell.payload_manager.clear_payload()
 
         reply_content[u'status'] = status
         # Compute the execution counter so clients can display prompts
@@ -237,6 +234,14 b' class Kernel(Configurable):'
             reply_content[u'user_variables'] = {}
             reply_content[u'user_expressions'] = {}
             
+        # Payloads should be retrieved regardless of outcome, so we can both
+        # recover partial output (that could have been generated early in a
+        # block, before an error) and clear the payload system always.
+        reply_content[u'payload'] = shell.payload_manager.read_payload()
+        # Be agressive about clearing the payload because we don't want
+        # it to sit in memory until the next execute_request comes in.
+        shell.payload_manager.clear_payload()
+
         # Send the reply.
         reply_msg = self.session.msg(u'execute_reply', reply_content, parent)
         io.raw_print(reply_msg)
@@ -571,7 +576,8 b" given, the GUI backend is matplotlib's, otherwise use one of: \\"
     kernel = make_kernel(namespace, kernel_class, OutStream)
 
     if namespace.pylab:
-        pylabtools.import_pylab(kernel.shell.user_ns)
+        pylabtools.import_pylab(kernel.shell.user_ns, backend,
+                                shell=kernel.shell)
 
     start_kernel(namespace, kernel)
 

IPython/zmq/pylab/backend_payload_svg.py

@@ -3,11 +3,13 b''
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
+from __future__ import print_function
 
 # Standard library imports
 from cStringIO import StringIO
 
 # System library imports.
+import matplotlib
 from matplotlib.backends.backend_svg import new_figure_manager
 from matplotlib._pylab_helpers import Gcf
 
@@ -18,17 +20,68 b' from backend_payload import add_plot_payload'
 # Functions
 #-----------------------------------------------------------------------------
 
-def show():
-    """ Deliver a SVG payload.
+def show(close=True):
+    """Show all figures as SVG payloads sent to the IPython clients.
+
+    Parameters
+    ----------
+    close : bool, optional
+      If true, a ``plt.close('all')`` call is automatically issued after
+      sending all the SVG figures.
     """
     for figure_manager in Gcf.get_all_fig_managers():
+        send_svg_canvas(figure_manager.canvas)
+    if close:
+        matplotlib.pyplot.close('all')
+
+# This flag will be reset by draw_if_interactive when called
+show._draw_called = False
+
+
+def paste(*figs):
+    """Paste figures into the console workspace.
+
+    If no arguments are given, all available figures are pasted.  If the
+    argument list contains references to invalid figures, a warning is printed
+    but the function continues pasting further figures.
+
+    Parameters
+    ----------
+    figs : tuple
+      A tuple that can contain any mixture of integers and figure objects.
+    """
+    if not figs:
+        show(close=False)
+    else:
+        fig_managers = Gcf.get_all_fig_managers()
+        fig_index = dict( [(fm.canvas.figure, fm.canvas) for fm in fig_managers]
+           + [ (fm.canvas.figure.number, fm.canvas) for fm in fig_managers] )
+
+        for fig in figs:
+            canvas = fig_index.get(fig)
+            if canvas is None:
+                print('Warning: figure %s not available.' % fig)
+            else:
+                send_svg_canvas(canvas)
+
+
+def send_svg_canvas(canvas):
+    """Draw the current canvas and send it as an SVG payload.
+    """
         # Make the background transparent.
         # figure_manager.canvas.figure.patch.set_alpha(0.0)
-        # Set the background to white instead so it looks good on black.
-        figure_manager.canvas.figure.set_facecolor('white')
-        figure_manager.canvas.figure.set_edgecolor('white')
-        data = svg_from_canvas(figure_manager.canvas)
-        add_plot_payload('svg', data)
+
+    # Set the background to white instead so it looks good on black.  We store
+    # the current values to restore them at the end.
+    fc = canvas.figure.get_facecolor()
+    ec = canvas.figure.get_edgecolor()
+    canvas.figure.set_facecolor('white')
+    canvas.figure.set_edgecolor('white')
+    try:
+        add_plot_payload('svg', svg_from_canvas(canvas))
+    finally:
+        canvas.figure.set_facecolor(fc)
+        canvas.figure.set_edgecolor(ec)
 
 
 def svg_from_canvas(canvas):
@@ -37,3 +90,23 b' def svg_from_canvas(canvas):'
     string_io = StringIO()
     canvas.print_svg(string_io)
     return string_io.getvalue()
+
+
+def draw_if_interactive():
+    """
+    Is called after every pylab drawing command
+    """
+    # We simply flag we were called and otherwise do nothing.  At the end of
+    # the code execution, a separate call to show_close() will act upon this.
+    show._draw_called = True
+
+
+def flush_svg():
+    """Call show, close all open figures, sending all SVG images.
+
+    This is meant to be called automatically and will call show() if, during
+    prior code execution, there had been any calls to draw_if_interactive.
+    """
+    if show._draw_called:
+        show(close=True)
+        show._draw_called = False