# SpikeGeneratorGroup class¶

(Shortest import: from brian2 import SpikeGeneratorGroup)

class brian2.input.spikegeneratorgroup.SpikeGeneratorGroup(N, indices, times, dt=None, clock=None, period=0 * second, when='thresholds', order=0, sorted=False, name='spikegeneratorgroup*', codeobj_class=None)[source]

A group emitting spikes at given times.

Parameters

N : int

The number of “neurons” in this group

indices : array of integers

The indices of the spiking cells

times : Quantity

The spike times for the cells given in indices. Has to have the same length as indices.

period : Quantity, optional

If this is specified, it will repeat spikes with this period. A period of 0s means not repeating spikes.

dt : Quantity, optional

The time step to be used for the simulation. Cannot be combined with the clock argument.

clock : Clock, optional

The update clock to be used. If neither a clock, nor the dt argument is specified, the defaultclock will be used.

when : str, optional

When to run within a time step, defaults to the 'thresholds' slot.

order : int, optional

The priority of of this group for operations occurring at the same time step and in the same scheduling slot. Defaults to 0.

sorted : bool, optional

Whether the given indices and times are already sorted. Set to True if your events are already sorted (first by spike time, then by index), this can save significant time at construction if your arrays contain large numbers of spikes. Defaults to False.

Notes

• If sorted is set to True, the given arrays will not be copied (only affects runtime mode)..

Attributes

 _neuron_index Array of spiking neuron indices. _previous_dt Remember the dt we used the last time when we checked the spike bins to not repeat the work for multiple runs with the same dt _spike_time Array of spiking neuron times. _spikes_changed “Dirty flag” that will be set when spikes are changed after the before_run check spikes The spikes returned by the most recent thresholding operation.

Methods

 before_run(run_namespace) Optional method to prepare the object before a run. set_spikes(indices, times[, period, sorted]) Change the spikes that this group will generate.

Details

_neuron_index

Array of spiking neuron indices.

_previous_dt

Remember the dt we used the last time when we checked the spike bins to not repeat the work for multiple runs with the same dt

_spike_time

Array of spiking neuron times.

_spikes_changed

“Dirty flag” that will be set when spikes are changed after the before_run check

spikes

The spikes returned by the most recent thresholding operation.

before_run(run_namespace)[source]

Optional method to prepare the object before a run.

Called by Network.after_run before the main simulation loop starts.

set_spikes(indices, times, period=0 * second, sorted=False)

Change the spikes that this group will generate.

This can be used to set the input for a second run of a model based on the output of a first run (if the input for the second run is already known before the first run, then all the information should simply be included in the initial SpikeGeneratorGroup initializer call, instead).

Parameters

indices : array of integers

The indices of the spiking cells

times : Quantity

The spike times for the cells given in indices. Has to have the same length as indices.

period : Quantity, optional

If this is specified, it will repeat spikes with this period. A period of 0s means not repeating spikes.

sorted : bool, optional

Whether the given indices and times are already sorted. Set to True if your events are already sorted (first by spike time, then by index), this can save significant time at construction if your arrays contain large numbers of spikes. Defaults to False.