Delete similar values in an array python numpy-CodePudding

Is there an easy possibility to delete similar values in an array (with condition) without using a for loop? For example lets say I have an array

np.array([1.2, 3.4, 3.5, 8.9, 10.9])

In this case, i would set the condition for example difference < 0.3 and get as an output

np.array([1.2, 3.4, 8.9, 10.9])

I haven't seen anything on the internet similar to this question. Of course there is the function .unique() but that is only for exactly the same values.

CodePudding user response：

If you want to delete the successive values, you can compute the successive differences and perform boolean indexing:

a = np.array([1.2, 3.4, 3.5, 8.9, 10.9])

out = a[np.r_[True, np.diff(a)>=0.3]]

Or, if you want the absolute difference:

out = a[np.r_[True, np.abs(np.diff(a))>=0.3]]

Output:

array([ 1.2,  3.4,  8.9, 10.9])

Intermediates:

np.diff(a)
# array([2.2, 0.1, 5.4, 2. ])

np.diff(a)>=0.3
# array([ True, False,  True,  True])

np.r_[True, np.diff(a)>=0.3]
# array([ True,  True, False,  True,  True])