textConnection {base}

R Documentation

Text Connections

Description

Input and output text connections.

Usage

textConnection(object, open = "r")

Arguments

object	character. A description of the connection. For an input is an R character vector object, and for an output connection the name for the R character vector to receive the output.
open	character. Either "r" (or equivalently "") for an input connection or "w" or "a"for an output connection.

Details

An input text connection is opened and the character vector is copied at time the connection object is created, and close destroys the copy.

An output text connection is opened and creates an R character vector of the given name in the user's workspace. This object will at all times hold the completed lines of output to the connection, and isIncomplete will indicate if there is an incomplete final line. Closing the connection will output the final line, complete or not.

Opening a text connection with mode = "a" will attempt to append to an existing character vector with the given name in the user's workspace. If none is found (even if an object exists of the right name but the wrong type) a new character vector wil be created, with a warning.

You cannot seek on a text connection, and seek will always return zero as the position.

Value

A connection object of class "textConnection" which inherits from class "connection".

See Also

connections, showConnections, pushBack

Examples

zz <- textConnection(LETTERS)
readLines(zz, 2)
scan(zz, "", 4)
pushBack(c("aa", "bb"), zz)
scan(zz, "", 4)
close(zz)

zz <- textConnection("foo", "w")
writeLines(c("testit1", "testit2"), zz)
cat("testit3 ", file=zz)
isIncomplete(zz)
cat("testit4\n", file=zz)
isIncomplete(zz)
close(zz)
foo

## Not run: # capture R output: use part of example from help(lm)
zz <- textConnection("foo", "w")
ctl <- c(4.17, 5.58, 5.18, 6.11, 4.5, 4.61, 5.17, 4.53, 5.33, 5.14)
trt <- c(4.81, 4.17, 4.41, 3.59, 5.87, 3.83, 6.03, 4.89, 4.32, 4.69)
group <- gl(2, 10, 20, labels = c("Ctl", "Trt"))
weight <- c(ctl, trt)
sink(zz)
anova(lm.D9 <- lm(weight ~ group))
cat("\nSummary of Residuals:\n\n")
summary(resid(lm.D9))
sink()
close(zz)
cat(foo, sep = "\n")

## End(Not run)

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