I have an array like this numpy array
dd =[[0.567 2 0.611] [0.469 1 0.479] [0.220 2 0.269] [0.480 1 0.508] [0.324 1 0.324]] I need 2 seperate array dd[:,1] ==1 and dd[:,1] ==2
These array are what I am after:
na =[[0.469 1 0.479] [0.480 1 0.508] [0.324 1 0.324]] na2 =[[0.567 2 0.611] [0.220 2 0.269]] I have tried np.where did really work
You could use numpy fancy indexing:
[~/repo/py] |32>dd[dd[:,1] == 1] [32] array([[ 0.469, 1. , 0.479], [ 0.48 , 1. , 0.508], [ 0.324, 1. , 0.324]]) [~/repo/py] |33>dd[dd[:,1] == 2] [33] array([[ 0.567, 2. , 0.611], [ 0.22 , 2. , 0.269]]) Alternatively you could use a list comprehension:
[~/repo/py] |21>np.array([row for row in dd if row[1] == 1]) [21] array([[ 0.469, 1. , 0.479], [ 0.48 , 1. , 0.508], [ 0.324, 1. , 0.324]]) [~/repo/py] |22>np.array([row for row in dd if row[1] == 2]) [22] array([[ 0.567, 2. , 0.611], [ 0.22 , 2. , 0.269]]) edit:
how to time these things in ipython:
[~/repo/py] |36>timeit dd[dd[:,1] == 1] 100000 loops, best of 3: 6 us per loop [~/repo/py] |37>timeit np.array([row for row in dd if row[1] == 1]) 100000 loops, best of 3: 11.5 us per loop