[SciPy-user] math operations on sparse matrices

josef.pktd@gmai... josef.pktd@gmai...
Sat Feb 21 13:28:51 CST 2009


I have a (dok) sparse distance matrix and I would like to take the
exponential of the distances

The direct method doesn't work
>>> Mexp = np.exp(-M)
Traceback (most recent call last):
  File "<pyshell#31>", line 1, in <module>
    Mexp = np.exp(-M)
AttributeError: exp

The following seems to work. What is the recommended way for doing
these transformations?
I didn't see anything in the docs.

>>> T1 = ssp.KDTree(xs3[::k,:],leafsize=2)
>>> M = T1.sparse_distance_matrix(T1, r)
>>> Mexp = M.copy()
>>> for k,v in M.items():
	Mexp[k]=np.exp(-v)

thanks,
Josef


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