[bug] error while plotting spikes with SpikeMonitor

[dokato]

Running an example from the tutorial:

from brian2 import *
start_scope()

N = 100
tau = 10*ms
eqs = '''
dv/dt = (2-v)/tau : 1
'''

G = NeuronGroup(N, eqs, threshold='v>1', reset='v=0', method='exact')
G.v = 'rand()'

spikemon = SpikeMonitor(G)

run(50*ms)

plot(spikemon.t/ms, spikemon.i, '.k')
xlabel('Time (ms)')
ylabel('Neuron index')

I get an error on plotting

    497 if x.shape[0] != y.shape[0]:
    498     raise ValueError(f"x and y must have same first dimension, but "
    499                      f"have shapes {x.shape} and {y.shape}")
--> 500 if x.ndim > 2 or y.ndim > 2:
    501     raise ValueError(f"x and y can be no greater than 2D, but have "
    502                      f"shapes {x.shape} and {y.shape}")
    503 if x.ndim == 1:

AttributeError: 'VariableView' object has no attribute 'ndim'

my brian2 installed from conda on mac m1 is on version 2.5.0.3.

[mstimberg]

Thanks for the report, this problem seems to have been triggered by changes in matplotlib 3.5.2 (released yesterday), the code runs fine with matplotlib 3.5.1. A simple workaround is to provide a standard numpy array instead of Brian's VariableView to the plot function:

plot(spikemon.t/ms, spikemon.i[:], '.k')