liuqiwu7 小白求助,R安装vcd包时出错 `> install.packages("vcd") --- 在此連線階段时请选用CRAN的鏡子 --- 警告: 无法在貯藏處http://mirror.bjtu.edu.cn/cran/bin/windows/contrib/3.1中读写索引 警告信息: package ‘vcd’ is not available (as a binary package for R version 3.1.3) >