| gzcon {base} | R Documentation |
gzcon provides a modified connection that wraps an existing
connection, and decompresses reads or compresses writes through that
connection. Standard gzip headers are assumed.
gzcon(con, level = 6, allowNonCompressed = TRUE)
con |
a connection. |
level |
integer between 0 and 9, the compression level when writing. |
allowNonCompressed |
logical. When reading, should
non-compressed files (lacking the gzip magic header) be allowed? |
If con is open then the modified
connection is opened. Closing the
wrapper connection will also close the underlying connection.
Reading from a connection which does not supply a gzip magic
header is equivalent to reading from the original connection if
allowNonCompressed is true, otherwise an error.
The original connection is unusable: any object pointing to it will now refer to the modified connection.
An object inheriting from class "connection". This is the same
connection number as supplied, but with a modified internal structure.
## Not run:
## This example may not still be available
## print the value to see what objects were created.
con <- url("http://hesweb1.med.virginia.edu/biostat/s/data/sav/kprats.sav")
print(load(con))
## End(Not run)
## gzfile and gzcon can inter-work.
## Of course here one would used gzfile, but file() can be replaced by
## any other connection generator.
zz <- gzfile("ex.gz", "w")
cat("TITLE extra line", "2 3 5 7", "", "11 13 17", file = zz, sep = "\n")
close(zz)
readLines(zz <- gzcon(file("ex.gz")))
close(zz)
unlink("ex.gz")
zz <- gzcon(file("ex.gz", "wb"))
cat("TITLE extra line", "2 3 5 7", "", "11 13 17", file = zz, sep = "\n")
close(zz)
readLines(zz <- gzfile("ex.gz"))
close(zz)
unlink("ex.gz")