depcache-package {depcache} | R Documentation |
Hash an expression with its dependencies and store its value, reloading it from a file as long as both the expression and its dependencies stay the same.
The functions in this package take an expression, walk its code to find its dependencies and calculate a hash of them. If a corresponding file already exists, it is loaded; otherwise, the expression is evaluated and its value is saved in the file. Optionally, this check may be performed every time a variable is accessed.
By default, a subdirectory of the current directory is used to store the cache files.
Index of help topics:
cache Evaluate an expression and cache its results depcache-package Cache R Expressions, Taking Their Dependencies into Account depcache.options Caching options setCached Cache-tracking assignment
Ivan Krylov
FNV-1a hash: http://www.isthe.com/chongo/tech/comp/fnv/
a <- 1
# will evaluate expression
cache({ message('evaluating expression'); a + 1 }) # 2
# will reuse cached value
x %<-% { message('evaluating expression'); a + 1 } # 2
x
a <- 2
# will recalculate the value
x # 3