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df019_Cache.py File Reference

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 df019_Cache
 

Detailed Description

View in nbviewer Open in SWAN This tutorial shows how the content of a data frame can be cached in memory in form of a data frame. The content of the columns is stored in memory in contiguous slabs of memory and is "ready to use", i.e. no ROOT IO operation is performed.

Creating a cached data frame storing all of its content deserialised and uncompressed in memory is particularly useful when dealing with datasets of a moderate size (small enough to fit the RAM) over which several explorative loops need to be performed at as fast as possible. In addition, caching can be useful when no file on disk needs to be created as a side effect of checkpointing part of the analysis.

All steps in the caching are lazy, i.e. the cached data frame is actually filled only when the event loop is triggered on it.

Definition in file df019_Cache.py.