R/AAAinstalled.R

In arulesCBA: Classification Based on Association Rules

#######################################################################
# Helper for using optional packages
# Copyright (C) 2015 Michael Hahsler
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.


.installed <-
  function(pkg)
    ! is(try(utils::installed.packages()[pkg, ],
      silent = TRUE)
      , "try-error")