How to Skip two Array Elements with same length?

I have 2 arrays which are the same length, but there are some elements in each array that are not given (data was not recorded). This is what I have right now. I use ~ and it is not working and just gives me one 0 when I have ~~~ (3 skipped elements). Is there anything I can use besides ~ ?

x=[1.2 2.6 2.8 6.1 6.5 ~ ~ ~ 2.1 5.86 ~ ~ 3.4]
y=[2.5 ~ 1.2 5.96 ~ ~ 2.95 3.1 0.2 3.4 5.21 9.68 1.4] 

Answer 1

[Yongjian Feng]

Use NaN?

[Din N]

Nice! Thank you

Answer 2

[Steven Lord]

Often missing data is represented using NaN or missing.

[Din N]

nice, thank you!