The ras file format is a human readable ASCII file format to encode spiking activity from a population of numbered neurons. The format is a space separated list containing “time neuronnumber” pairs, of which time is given in seconds and the neuron id is given as integer:

5.680800  2120
5.683600  496
5.685500  1936
5.693700  2464
5.700700  1856
5.716600  1464

The neuron number refers to the NeuronID within a SpikingGroup. The suggested file extension “ras” and as it is used for created by the SpikeMonitor.

When running in parallel you will often encounter having to merge the ras files from multiple ranks (e.g. output.X.ras). This can be done efficiently using linux sort program

sort -g -m output.*.ras > output.ras