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I am pretty new to Python and am trying to use some code I found online for an undergrad physics project. This code includes the clifford library, which is causing my problems. Given the syntax of the code and the fact that I installed it using pip3, it should be Python 3.

After running this code:

from __future__ import division
import numpy
from clifford import *
layout, blades = Cl(3,0)
e0, e1, e2 = [blades['e%i'%k] for k in range(3)]
I = (e0^e1^e2)

I get the following traceback:

Traceback (most recent call last):
  File "/Users/melissa/Documents/Fodje.py", line 5, in <module>
    e0, e1, e2 = [blades['e%i'%k] for k in range(3)]
  File "/Users/melissa/Documents/Fodje.py", line 5, in <listcomp>
    e0, e1, e2 = [blades['e%i'%k] for k in range(3)]
KeyError: 'e0'

I asked my CS professor and he said there is likely a problem with the indexing in blades.

Can anyone help me in trying to troubleshoot this issue? Thanks!

The full code is here The Clifford docs are here.

q-compute
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1 Answers1

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The problem here is that the dict object blades contains keys e1, e2, e3 and so on. The range() function starts at 0, so range(3) essentially returns the list [0,1,2] - (its actually an ittarator not a list, but you don't need to worry about that).

The reason you are getting a key Error is, python is looking in blades for the key e0 and it doesn't exist. replace k with k+1 and it should work.

e.g.e1, e2, e3 = [blades['e%i'%(k+1)] for k in range(3)]

In general if your trying to troubleshoot yourself, a key Error means your trying to look up something that isn't there. So a good idea might be to print that object. So to diagnose what was wrong here I just did print(blades) and it became clear. I hope this helps.

The full code would be:

from __future__ import division
import numpy
from clifford import *
layout, blades = Cl(3,0)
e1, e2, e3 = [blades['e%i'%(k+1)] for k in range(3)]
I = (e1^e2^e3)
tim-mccurrach
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