content: # -*- coding: utf-8 -*-
  #
  # connex_ew.py
  #
  # This file is part of NEST.
  #
  # Copyright (C) 2004 The NEST Initiative
  #
  # NEST is free software: you can redistribute it and/or modify
  # it under the terms of the GNU General Public License as published by
  # the Free Software Foundation, either version 2 of the License, or
  # (at your option) any later version.
  #
  # NEST 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 General Public License for more details.
  #
  # You should have received a copy of the GNU General Public License
  # along with NEST.  If not, see <http://www.gnu.org/licenses/>.
  
  """
  NEST spatial example
  --------------------
  
  Create two populations of iaf_psc_alpha neurons on a 30x30 grid with edge_wrap,
  connect with circular mask, flat probability,
  visualize.
  
  BCCN Tutorial @ CNS*09
  Hans Ekkehard Plesser, UMB
  """
  
  import matplotlib.pyplot as plt
  import numpy as np
  import nest
  
  nest.ResetKernel()
  
  pos = nest.spatial.grid(shape=[30, 30], extent=[3., 3.], edge_wrap=True)
  
  #######################################################################
  # create and connect two populations
  a = nest.Create('iaf_psc_alpha', positions=pos)
  b = nest.Create('iaf_psc_alpha', positions=pos)
  
  cdict = {'rule': 'pairwise_bernoulli',
           'p': 0.5,
           'mask': {'circular': {'radius': 0.5}}}
  
  nest.Connect(a, b,
               conn_spec=cdict,
               syn_spec={'weight': nest.random.uniform(0.5, 2.)})
  
  plt.clf()
  
  #####################################################################
  # plot targets of neurons in different grid locations
  
  # first, clear existing figure, get current figure
  plt.clf()
  fig = plt.gcf()
  
  # plot targets of two source neurons into same figure, with mask
  for src_index in [30 * 15 + 15, 0]:
      # obtain node id for center
      src = a[src_index:src_index + 1]
      nest.PlotTargets(src, b, mask=cdict['mask'], fig=fig)
  
  # beautify
  plt.axes().set_xticks(np.arange(-1.5, 1.55, 0.5))
  plt.axes().set_yticks(np.arange(-1.5, 1.55, 0.5))
  plt.grid(True)
  plt.axis([-2.0, 2.0, -2.0, 2.0])
  plt.axes().set_aspect('equal', 'box')
  plt.title('Connection targets')
  
  plt.show()
  
  # plt.savefig('connex_ew.pdf')
  