How to get index of array type rule input

Thank you all for your responses, I will try to elaborate what I am trying to achieve.

I have a local variable which stores multiple item(stored in record A) with its quantity selected by user, on the next page I want to show inventory(stored in record B) with required quantity to build item stored in local variable, in order to do so I need to compare item name with data stored in record B, I am trying to create rule input of Local variable in different page and then compare it with record type B(I am using grid Layout).

Please help me weather my approach is correct? if correct how should I compare it?

Thank you all for your responses, I will try to elaborate what I am trying to achieve.

I have a local variable which stores multiple item(stored in record A) with its quantity selected by user, on the next page I want to show inventory(stored in record B) with required quantity to build item stored in local variable, in order to do so I need to compare item name with data stored in record B, I am trying to create rule input of Local variable in different page and then compare it with record type B(I am using grid Layout).

Please help me weather my approach is correct? if correct how should I compare it?

Do you have any relationship between these two records ? That could help you extract the information you are looking for. 

you can use displayvalue function.

docs.appian.com/.../fnc_conversion_displayvalue.html