Test whether an ff or ffdf object or a ff_pointer is opened.
ff_pointer
is.open(x, …) # S3 method for ff is.open(x, …) # S3 method for ffdf is.open(x, …) # S3 method for ff_pointer is.open(x, …)
an ff or ffdf object
ff
ffdf
further arguments (not used)
TRUE or FALSE (or NA if not all components of an ffdf object are opened or closed)
ff objects open automatically if accessed while closed. For ffdf objects we test all of their physical components including their row.names if they are is.ff
physical
row.names
is.ff
is.readonly, open.ff, close.ff
is.readonly
open.ff
close.ff
# NOT RUN { x <- ff(1:12) is.open(x) close(x) is.open(x) rm(x); gc() # }
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