r - 无法安装 rgdal 包

Question

我必须使用 shapefile 并将它们转换为光栅，rgdal建议使用该包，但该包无法识别（R v2.11、RStudio 0.98.501、Mac OS X 10_7_5）。我怎么还能安装rgdal或省略这个包？

为了进一步澄清我的问题，错误消息是：

> install.packages("rgdal")
Warning in install.packages :
  cannot open: HTTP status was '404 Not Found'
Warning in install.packages :
  cannot open: HTTP status was '404 Not Found'
Warning in install.packages :
  unable to access index for repository http://www.stats.ox.ac.uk/pub/RWin/bin/macosx/leopard/contrib/2.11
Warning in install.packages :
  argument 'lib' is missing: using '/Users/myname/Library/R/2.11/library'
Warning in install.packages :
  cannot open: HTTP status was '404 Not Found'
Warning in install.packages :
  cannot open: HTTP status was '404 Not Found'
Warning in install.packages :
  unable to access index for repository http://www.stats.ox.ac.uk/pub/RWin/bin/macosx/leopard/contrib/2.11
Warning in install.packages :
  package ‘rgdal’ is not available