Close frees the Memory Mapping resources and closes the ff file without deleting the file data.
● Data Source:
CranContrib
● Keywords: IO, data
● Alias: close.ff, close.ff_pointer, close.ffdf
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ff
(Package: ff) :
ff classes for representing (large) atomic data
The ff package provides atomic data structures that are stored on disk but behave (almost) as if they were in RAM by mapping only a section (pagesize) into main memory (the effective main memory consumption per ff object). Several access optimization techniques such as Hyrid Index Preprocessing (as.hi, update.ff) and Virtualization (virtual, vt, vw) are implemented to achieve good performance even with large datasets. In addition to the basic access functions, the ff package also provides compatibility functions that facilitate writing code for ff and ram objects (clone, as.ff, as.ram) and very basic support for operating on ff objects (ffapply). While the (possibly packed) raw data is stored on a flat file, meta informations about the atomic data structure such as its dimension, virtual storage mode (vmode), factor level encoding, internal length etc.. are stored as an ordinary R object (external pointer plus attributes) and can be saved in the workspace. The raw flat file data encoding is always in native machine format for optimal performance and provides several packing schemes for different data types such as logical, raw, integer and double (in an extended version support for more tighly packed virtual data types is supported). flatfile data files can be shared among ff objects in the same R process or even from different R processes due to Memory-Mapping, although the caching effects have not been tested extensively. Please do read and understand the limitations and warnings in LimWarn before you do anything serious with package ff.
Function ffindexget allows to extract elements from an ff vector according to positive integer suscripts stored in an ff vector. Function ffindexset allows the inverse operation: assigning to elements of an ff vector according to positive integer suscripts stored in an ff vector. These functions allow more control than the method dispatch of [ and [<- if an ff integer subscript is used.
● Data Source:
CranContrib
● Keywords: IO, data
● Alias: ffindexget, ffindexset
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splitPathFile splits a vector of pathfile-strings into path- and file-components without loss of information. unsplitPathFile restores the original pathfile-string vector. standardPathFile standardizes a vector of pathfile-strings: backslashes are replaced by slashes, except for the first two leading backslashes indicating a network share. tempPathFile returns - similar to tempfile - a vector of filenames given path(s) and file-prefix(es) and an optional extension. fftempfile returns - similar to tempPathFile - a vector of filenames following a vector of pathfile patterns that are intrepreted in a ff-specific way.
providing 
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