how to sort numpy 2D array with 2 elements: For example I have:
[['0.6435256766173603' 'some text']
['0.013180497307149886' 'some text2']
['0.017696632827641112' 'some text3']]
I need:
[['0.6435256766173603' 'some text']
['0.017696632827641112' 'some text3']
['0.013180497307149886' 'some text2']]
I tried np.argsort, np.sort, but it doesn't work! Any help will be appreciated
Assuming you want your array lexsorted by the 0th column, np.argsort is what you want.
out = x[np.argsort(x[:, 0])[::-1]]
print(out)
array([['0.6435256766173603', 'some text'],
['0.017696632827641112', 'some text3'],
['0.013180497307149886', 'some text2']],
a = np.array([['0.6435256766173603', 'some text'],
['0.013180497307149886', 'some text2'],
['0.017696632827641112', 'some text3']])
a[a[:, 0].argsort()[::-1]]
should yield
array([['0.6435256766173603', 'some text'],
['0.017696632827641112', 'some text3'],
['0.013180497307149886', 'some text2']],
dtype='|S20')
Breaking it down:
# the first column of `a`
a[:, 0]
# sorted indices of the first column, ascending order
a[:, 0].argsort() # [1, 2, 0]
# sorted indices of the first column, descending order
a[:, 0].argsort()[::-1] # [0, 2, 1]
# sort `a` according to the sorted indices from the last step
a[a[:, 0].argsort()[::-1]]
numpy.ndarraywith strings? You should probably just use normal Python lists...