This is A PREVIEW for NEST 3.0 and NOT an OFFICIAL RELEASE! Some functionality may not be available and information may be incomplete!

Store data in main memory

When a recording device sends data to the memory backend, it is stored internally in efficient vectors. These vectors are made available to the user level in the device’s status dictionary under the key events.

The events dictionary always contains the global IDs of the source nodes of the recorded data in the field sender. It also always contains the time of the recording. Depending on the setting of the property time_in_steps, this time can be stored in two different formats:

  • If time_in_steps is false (which is the default), the time is stored as a single floating point number in the field times, interpreted as the simulation time in ms

  • If time_in_steps is true, the time is stored as a pair consisting of the integer number of simulation time steps in units of the simulation resolution in times and the negative offset from the next such grid point as a floating point number in ms in offset.

All additional data collected or sampled by the recording device is contained in the events dictionary in arrays. These data are named based on the recordable they came from and with the appropriate data type (either integer or floating point).

The number of events that were collected by the memory backend can be read out of the n_events entry in the status dictionary of the recording device. To delete data from memory, n_events can be set to 0. Other values cannot be set.

Parameter summary


A dictionary containing the recorded data in the form of one numeric array for each quantity measured. It always has the sender global IDs of recorded events under the key senders and the time of the recording, the format of which depends on the setting of time_in_steps.


The number of events collected or sampled since the last reset of n_events. By setting n_events to 0, all events recorded so far will be discarded from memory.


A Boolean (default: false) specifying whether to store time in steps, i.e., in integer multiples of the simulation resolution (under the key times of the events dictionary) plus a floating point number for the negative offset from the next grid point in ms (under key offset), or just the simulation time in ms under key times. This property cannot be set after Simulate has been called.