# 4.3. Replay¶

One of the key functionalities of the cbcpost framework is the ability to replay problem. Consider the case where one wants to extract additional information from a simulation. Simulations are typically costly, and redoing simulations are not generally desired (or even feasible). This motivates the functionality to replay the simulation by loading the computed solution back into memory and compute additional fields.

This has several major benefits:

• Limit memory consumption of initial computation
• Compute quantities unsupported in parallel
• Compute costly, conditional quantities (e.g. not to be performed if simulation was unable to complete)
• Create visualization data

The interface to the replay module is minimal:

from cbcpost import PostProcessor, Replay

pp = PostProcessor(dict(casedir="ExistingResults/"))

In the replay module, all fields that are stored in a reloadable format will be treated as a solution. They will be passed to a postprocessor as instances of the Loadable-class. This makes sure that no unnecessary I/O-operations occur, as the stored data are only loaded when they are triggered in the postprocessor.