[Numpy-discussion] array operation
Dave Bazell
bazell at comcast.net
Tue Jan 21 12:33:35 CST 2003
I am trying to see if I can use where() or choose() to do this. I can't
really figure it out.
I have a 2-d array data where each row is an observation and each column is
an attribute of the observation:
data =
[[.3, .2, 2.3,...] <- observation 1
[.7, 1.2, .4...] <- observation 2
...]]
I have another 1-d array that contains a code for the class of object:
class = [0,1,0,1,1,3,2,0,...]
where class[i] = the class of the ith object in the data array. Thus,
observation 1 above is class 0, observation 2 is class 1, and so on.
I want to select all objects of a given class from data array. I can do
this with a loop
for i in range(ndat):
if class == 0:
do something
....
Is there a way to use where() or choose() to do this? Would it be more
efficient?
Thanks,
Dave
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