Update 2013-05-23-the-art-r-programming.md (#355)
Update 2013-05-23-the-art-r-programming.md (#355)

* Update 2013-05-23-the-art-r-programming.md

* Update 2013-05-23-the-art-r-programming.md

cosname/cosx.org,hetong007/cosx.org,yixuan/cosx.org,fyears/cosx.org,JianqiaoWang/cosx.org,Lchiffon/cosx.org,cosname/cosx.org,Lchiffon/cosx.org,hetong007/cosx.org,tomatoiscoding/cosx.org,Lchiffon/cosx.org,hetong007/cosx.org,fyears/cosx.org,yixuan/cosx.org,JianqiaoWang/cosx.org,tomatoiscoding/cosx.org,fyears/cosx.org,yixuan/cosx.org,JianqiaoWang/cosx.org,tomatoiscoding/cosx.org,cosname/cosx.org