require() does what you want. Run "?require" for details.
require() returns 'FALSE' and gives a warning (rather than an error as
'library()' does by default) if the package does not exist.
'require' returns (invisibly) a logical indicating whether the required
package is available. (You can capture the logical value by assigning it
to a variable, eg. tmp <- require("pkg_name"))
On 2010-8-27 9:07, pdb wrote:
Hi,
I am writing a function that requires a specific package to be installed.
Is there a way of checking if the package is installed and returning a TRUE
/ FALSE result so my function can return an appropriate error message and
exit the function gracefully rather than just bombing out?
I'm thinking along the following lines (but want code that works),
f_checkpackage<- function()
{
if (library(madeupname) == TRUE) {
cat("package loaded OK\n")
}
else
{
cat("ERROR: package not loaded")
}
}
f_checkpackage()
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