Price index objects — piar

There are several classes to represent price indexes.

All indexes inherit from the piar_index virtual class.
Period-over-period indexes that can be chained over time inherit from chainable_piar_index.
Fixed-base indexes inherit from direct_piar_index.

Details

The piar_index object is a list-S3 class with the following components:

index: A list with an entry for each period in time that gives a vector of index values for each level in levels.
contrib: A list with an entry for each period in time, which itself contains a list with an entry for each level in levels with a named vector that gives the additive contribution for each price relative.
levels: A character vector giving the levels of the index.
time: A character vector giving the time periods for the index.

The chainable_piar_index and direct_piar_index subclasses have the same structure as the piar_index class, but differ in the methods used to manipulate the indexes.