Remove non-conjugates from complex numbers list

Question

I have two lists, one contains the real part of imaginary numbers, the other contains the imaginary part of the same numbers. I want to remove from both lists the imaginary numbers that do not have a conjugate.

For example, the following lists x = [3, 4, 2, 7, 4] and y = [2, -1, 0, 6, 1] represent the numbers :

3 + 2j    <- no conjugate (to remove)
4 - 1j    <- conjugate (to keep)
2 + 0j    <- real (to keep)
4 + 1j    <- conjugate (to keep)
7 + 6j    <- no conjugate (to remove)

The expected result is the following :

new_x = [4, 2, 4]
new_y = [-1, 0, 1]

Any idea how i can achieve this ? Thanks

Answer 1

This script will find complex conjugates from lists x and y:

x = [3, 4, 2, 7, 4]
y = [2, -1, 0, 6, 1]

tmp = {}
for r, i in zip(x, y):
    tmp.setdefault(i, set()).add(r)

x_out, y_out = [], []
for r, i in zip(x, y):
    if i==0 or r in tmp.get(-i, []):
        x_out.append(r)
        y_out.append(i)

print(x_out)
print(y_out)

Prints:

[4, 2, 4]
[-1, 0, 1]