.. currentmodule:: brian

.. index::
   pair: example usage; raster_plot
   pair: example usage; SpikeMonitor
   pair: example usage; PoissonGroup
   pair: example usage; run

.. _example-misc_poisson:

Example: poisson (misc)
=======================

This example demonstrates the PoissonGroup object. Here we have
used a custom function to generate different rates at different
times.

This example also demonstrates a custom SpikeMonitor.

::

    #import brian_no_units # uncomment to run faster
    from brian import *
    
    # Rates
    
    r1 = arange(101, 201) * 0.1 * Hz
    r2 = arange(1, 101) * 0.1 * Hz
    
    def myrates(t):
        if t < 10 * second:
            return r1
        else:
            return r2
    # More compact: myrates=lambda t: (t<10*second and r1) or r2
    
    # Neuron group
    P = PoissonGroup(100, myrates)
    
    # Calculation of rates
    
    ns = zeros(len(P))
    
    def ratemonitor(spikes):
        ns[spikes] += 1
    
    Mf = SpikeMonitor(P, function=ratemonitor)
    M = SpikeMonitor(P)
    
    # Simulation and plotting
    
    run(10 * second)
    print "Rates after 10s:"
    print ns / (10 * second)
    
    ns[:] = 0
    run(10 * second)
    print "Rates after 20s:"
    print ns / (10 * second)
    
    raster_plot()
    show()