Question: what is the correct way to measure the compressed size?

[MikeB2019x]

The compress function returns a byte object and original size. But how to you see the new compressed size?
The reason I ask is because I am compressing tuples to do NCD on them. Below I show some example tuples, converted to a single string, and then the results of unishox2 compression [original size, len(unishox2.compress()[0])].
The challenge is that tuples of identical length all have the same compressed length regardless of differences e.g. all zeros. That is unexpected to me so I'm wondering if it is because i am measuring the compressed size incorrectly.

[131100, 131100] 131100131100 [12, 8]
[120100, 410100] 120100410100 [12, 8]
[131100, 510100, 800400] 131100510100800400 [18, 11]
[131150, 512100] 131150512100 [12, 8]