# -*- coding: utf-8 -*-
#
# if_curve.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/>.

"""
IF curve example
----------------

This example illustrates how to measure the I-F curve of a neuron.
The program creates a small group of neurons and injects a noisy current
:math:`I(t) = I_mean + I_std*W(t)`
where :math:`W(t)` is a white noise process.
The program systematically drives the current through a series of  values in
the two-dimensional `(I_mean, I_std)` space and measures the firing rate of
the neurons.

In this example, we measure the I-F curve of the adaptive exponential
integrate and fire neuron (``aeif_cond_exp``), but any other neuron model that
accepts current inputs is possible. The model and its parameters are
supplied when the IF_curve object is created.

"""

import numpy
import nest
import shelve

###############################################################################
# Here we define which model and the neuron parameters to use for measuring
# the transfer function.

model = 'aeif_cond_exp'
params = {'a': 4.0,
          'b': 80.8,
          'V_th': -50.4,
          'Delta_T': 2.0,
          'I_e': 0.0,
          'C_m': 281.0,
          'g_L': 30.0,
          'V_reset': -70.6,
          'tau_w': 144.0,
          't_ref': 5.0,
          'V_peak': -40.0,
          'E_L': -70.6,
          'E_ex': 0.,
          'E_in': -70.}


class IF_curve():

    t_inter_trial = 200.  # Interval between two successive measurement trials
    t_sim = 1000.         # Duration of a measurement trial
    n_neurons = 100       # Number of neurons
    n_threads = 4         # Nubmer of threads to run the simulation

    def __init__(self, model, params=None):
        self.model = model
        self.params = params
        self.build()
        self.connect()

    def build(self):
        #######################################################################
        #  We reset NEST to delete information from previous simulations
        # and adjust the number of threads.

        nest.ResetKernel()
        nest.local_num_threads = self.n_threads

        #######################################################################
        # We create neurons and devices with specified parameters.

        self.neuron = nest.Create(self.model, self.n_neurons, self.params)
        self.noise = nest.Create('noise_generator')
        self.spike_recorder = nest.Create('spike_recorder')

    def connect(self):
        #######################################################################
        # We connect the noisy current to the neurons and the neurons to
        # the spike recorders.

        nest.Connect(self.noise, self.neuron, 'all_to_all')
        nest.Connect(self.neuron, self.spike_recorder, 'all_to_all')

    def output_rate(self, mean, std):
        self.build()
        self.connect()

        #######################################################################
        # We adjust the parameters of the noise according to the current
        # values.

        self.noise.set(mean=mean, std=std, start=0.0, stop=1000., origin=0.)

        # We simulate the network and calculate the rate.

        nest.Simulate(self.t_sim)
        rate = self.spike_recorder.n_events * 1000. / (1. * self.n_neurons * self.t_sim)
        return rate

    def compute_transfer(self, i_mean=(400.0, 900.0, 50.0),
                         i_std=(0.0, 600.0, 50.0)):
        #######################################################################
        # We loop through all possible combinations of `(I_mean, I_sigma)`
        # and measure the output rate of the neuron.

        self.i_range = numpy.arange(*i_mean)
        self.std_range = numpy.arange(*i_std)
        self.rate = numpy.zeros((self.i_range.size, self.std_range.size))
        nest.set_verbosity('M_WARNING')
        for n, i in enumerate(self.i_range):
            print('I  =  {0}'.format(i))
            for m, std in enumerate(self.std_range):
                self.rate[n, m] = self.output_rate(i, std)


transfer = IF_curve(model, params)
transfer.compute_transfer()

###############################################################################
# After the simulation is finished, we store the data into a file for
# later analysis.

with shelve.open(model + '_transfer.dat') as dat:
    dat['I_mean'] = transfer.i_range
    dat['I_std'] = transfer.std_range
    dat['rate'] = transfer.rate
