CODEWITHSUNDEEP
pythonperformancenumpy
user3607022
user3607022

Reputation: 482

Remove duplicate coordinates stored in arrays in python

I am storing 3d coordinates in three arrays. Below follows an example of a total of four entries of coordinate points, of the coordinates (1,2,3), (2,3,4) and (3,4,5), where the first coordinate point is duplicated.

x = [1, 2, 3, 1]
y = [2, 3, 4, 2]
z = [3, 4, 5, 3]

Now, I would like to as efficiently as possible remove duplicate coordinates, such that the above arrays result in

x_prime = [1, 2, 3]
y_prime = [2, 3, 4]
z_prime = [3, 4, 5]

...still containing the same coordinates (1,2,3), (2,3,4) and (3,4,5) however with no duplicate entry of (1,2,3)

Upvotes: 0

Views: 642

Answers (3)

tomtomfox
tomtomfox

Reputation: 304

In pure python:

x_prime = list(dict([e, 0] for e in x).keys())

EDIT:

Mustafa Aydin's solution in the comments is even simpler :

list(dict.fromkeys(x))

Upvotes: 2

Sawradip Saha
Sawradip Saha

Reputation: 1431

I guess this is a simple, pythonic and linear solution of your problem. Please let me know the performance.

l = []
for a, b, c in zip(x, y, z):
    l.append((a, b, c))

x_prime = []
y_prime = []
z_prime = []

for a, b, c in set(l):
    x_prime.append(a)
    y_prime.append(b)
    z_prime.append(c)

Upvotes: 1

akuiper
akuiper

Reputation: 215047

You can use np.unique(..., axis=0):

np.unique(np.array([x, y, z]).T, axis=0)
# [[1 2 3]
#  [2 3 4]
#  [3 4 5]]

If you need to unpack the result:

x_prime, y_prime, z_prime = np.unique(np.array([x, y, z]).T, axis=0)

x_prime
# [1 2 3]

y_prime
# [2 3 4]

z_prime
# [3 4 5]

Upvotes: 1

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