You will need to install CRF++ prior to installing the CRFPP gem; simply download the sources, unpack them, and then execute the following commands:
$ cd CRF++-0.54 $ make $ [sudo] make install $ [sudo] gem install crfpp
If you are using a Debian-based system, you may want to try the Ubuntu packages from Ubunutu NLP Repository:
$ sudo apt-get install libcrf++ $ [sudo] gem install crfpp
Alternatively, if you are using homebrew on OS X you may prefer to:
$ brew install crf++ $ gem install crfpp
NB: if you installed CRF++ yourself make sure to not install (or not to load) the Ruby extensions that are packaged with the sources as they may interfere with the crfpp gem.
Copyright 2011 Sylvester Keil. All rights reserved.
CRFPP is published under a BSD License; see the LICENSE file for details.