Question

I have the following array of data

In [56]:data
Out[56]: 
array([[  4360.,   6178.],
       [ 10906.,  14956.],
       [  5071.,   8963.],
       ..., 
       [ 16019.,  12300.],
       [ 12306.,   3327.],
       [ 13663.,  12641.]])

I want to store in a all the rows whose zeroth element is less than some value value1 and higher than some other value value2.

I have try the following

d[ 9057 > d[0::,0] > 8000, 0::]

and

d[d[0::,0] > 8000 and d[0::,0] < 9057, 0::]

but both are stopped by the following error

ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

Is there an efficient way for doing this? Thanks.

Answer 1

The following should do it:

d[(d[0::,0] > 8000) & (d[0::,0] < 9057), 0::]

By the way, you can replace all those 0:: with ::

d[(d[:,0] > 8000) & (d[:,0] < 9057)]

I find this a little easier on the eye.