安裝R包時，突然遇見如下錯誤
Warning in install.packages :
InternetOpenUrl failed: ''
Warning in install.packages :
InternetOpenUrl failed: ''
Warning in install.packages :
InternetOpenUrl failed: ''
Warning in install.packages :
unable to access index for repository https://mirrors.tuna.tsinghua.edu.cn/CRAN/src/contrib:
cannot open URL 'https://mirrors.tuna.tsinghua.edu.cn/CRAN/src/contrib/PACKAGES'
Installing package into ‘C:/Users/Administrator/Documents/R/win-library/3.6’
(as ‘lib’ is unspecified)
Warning in install.packages :
InternetOpenUrl failed: ''
Warning in install.packages :
InternetOpenUrl failed: ''
Warning in install.packages :
InternetOpenUrl failed: ''
Warning in install.packages :
unable to access index for repository https://mirrors.tuna.tsinghua.edu.cn/CRAN/src/contrib:
cannot open URL 'https://mirrors.tuna.tsinghua.edu.cn/CRAN/src/contrib/PACKAGES'
Warning in install.packages :
package ‘RIdeogram’ is not available (for R version 3.6.3)
Warning in install.packages :
InternetOpenUrl failed: ''
Warning in install.packages :
InternetOpenUrl failed: ''
Warning in install.packages :
InternetOpenUrl failed: ''
Warning in install.packages :
unable to access index for repository https://mirrors.tuna.tsinghua.edu.cn/CRAN/bin/windows/contrib/3.6:
cannot open URL 'https://mirrors.tuna.tsinghua.edu.cn/CRAN/bin/windows/contrib/3.6/PACKAGES'
Warning message:
R graphics engine version 12 is not supported by this version of RStudio. The Plots tab will be disabled until a newer version of RStudio is installed.
解決方法：
https://blog.csdn.net/xiangyong58/article/details/51980592
R語言鏡像訪問貌是通過IE瀏覽器，所以查看IE瀏覽器是否可以連上網，往往問題出在IE瀏覽器不能連網。將IE瀏覽器重新修復(方法參照百度)后加載安裝包就能成功運行了，順利加載。
IE瀏覽器重新修復：
https://jingyan.baidu.com/article/22fe7ced616e463002617f35.html