Continue after errors

try

Description

Evaluates a possible erroneous expression without exiting to the top-level prompt.

Usage

try(expr, silent = FALSE, outFile = getOption("try.outFile", default = stderr()))

Arguments

expr	An expression to evaluate. It is evaluated in the frame of the caller.
silent	A logical flag. If TRUE, the error message is not printed. If FALSE (the default), the error message is printed.
outFile	The name of a file or a connection object specifying where to print the error message.

Details

try is implemented using the tryCatch function, creating an "error" condition handler to catch any errors.

Value

returns the value of the expression if no error occurred while evaluating the expression. If an error occurred, invisibly returns an object of class "try-error" containing the error message, with an attribute "condition" containing the error condition caught.

See Also

tryCatch.

Examples

# avoid stopping simulation because of bad data points 
set.seed(1) 
inputs <- sapply(1:10, function(i)rpois(1,1)) 
f <- function(x) if(x<1) stop("x<1") else log(x) 
val <- lapply(inputs, function(x)try(f(x))) 
unlist(val[!sapply(val, is, "try-error")]) # extract ones that worked 
rm(x); rm(y)  # make sure x, y are not defined.
try(x)  
# Error in tryCatch(expr, error = function(e) invisible(.tryErrorHandle... : 
# object "x" not found
res <- try(x) 
# Error in tryCatch(expr, error = function(e) invisible(.tryErrorHandle... : 
# object "x" not found
class(res) # "try-error"
res1 <- try(y, silent = TRUE)  # no error printout
res1   # examine error
x <- runif(20) 
y <- rnorm(20)
res2 <- try(lm(x~y))
res2  # the value of lm(x~y)

Package base version 6.1.5-18
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