Error: "The truth value of an array with more than one element is ambiguous"

[mtewes]

As reported to us by a user: the following error is raised when running either of

pycs.sim.draw.multidraw(lcs, onlycopy=True, n=20, npkl=10, simset="copies")
pycs.sim.run.multirun("copies", lcs, myopt.spl, optset="spl1", tsrand=5.0)

Traceback:

Start
opt_ts_indi brute done
opt_ts_indi fine done
opt_ml done
opt_source BOK done
BA  +10.65    (Iteration 15, r2 =    377.9)
Timeshift stabilization and releasing of splflat :
BA  +10.65    (Iteration  1, r2 =    377.9)
BA  +10.65    (Iteration  2, r2 =    377.9)
BA  +10.65    (Iteration  3, r2 =    377.9)
BA  +10.65    (Iteration  4, r2 =    377.9)
BA  +10.65    (Iteration  5, r2 =    377.9)
Shifted 20 simulations, using 1 CPU, time : 11
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pycs/sim/run.py", line 435, in multirun
   rr = runresults(simlcslist, qs = qs, name="sims_%s_opt_%s" % (simset, optset))
 File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pycs/sim/run.py", line 130, in __init__
   if qs != None:
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

[mtewes]

We failed to follow the recommendation:

Comparisons to singletons like None should always be done with is or is not , never the equality operators.

https://www.python.org/dev/peps/pep-0008/#programming-recommendations

Let's pay attention to this, whenever we write a != None

[mtewes]

I've pushed a fix to master correcting the above issue. To anyone, let us know if other occurrences appear.

[vbonvin]

@mtewes, let's keep this issue open as a reminder to clean the whole code of such occurrences !