Anton Sherwood wrote: > This code -- > > adj = [ [eval(y) for y in x.split()] for x in infile ] > val,vec = numpy.linalg.eig(adj) > master = zip( val, vec.transpose() ) > master.sort() > > *sometimes* gives this error: > > Traceback (most recent call last): > File "3work.py", line 14, in <module> > master.sort() > ValueError: The truth value of an array with more > than one element is ambiguous. Use a.any() or a.all() > > What does sort() care about truth values?! >
The sort method on lists basically uses cmp(x,y) to determine sort order. In this case, I suspect you are getting errors whenever you have equal-valued eigenvalues so the comparison has to go to the second item in the tuple (which is the array). cmp(x,y) must return -1, 0, or 1 which doesn't work on arrays with more than 1 element because it is ambiguous. Thus you get this error. The operation is undefined. What do you actually want to do when you have equal-valued eigenvalues? -Travis _______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion
