无法在R中安装插入符号包

Question

当我尝试在RI中安装插入符号包时，出现以下错误消息：

utils:::menuInstallPkgs()

--- Please select a CRAN mirror for use in this session ---
Warning: failed to download mirrors file (cannot open URL 'https://cran.r-project.org/CRAN_mirrors.csv'); using local file 'C:/PROGRA~1/R/R-34~1.0/doc/CRAN_mirrors.csv'
Warning: unable to access index for repository https://rweb.crmda.ku.edu/cran/src/contrib:
  cannot open URL 'https://rweb.crmda.ku.edu/cran/src/contrib/PACKAGES'
Warning: unable to access index for repository http://www.stats.ox.ac.uk/pub/RWin/src/contrib:
  cannot open URL 'http://www.stats.ox.ac.uk/pub/RWin/src/contrib/PACKAGES'
Error in install.packages(NULL, .libPaths()[1L], dependencies = NA, type = type) : 
  no packages were specified
In addition: Warning message:
In download.file(url, destfile = f, quiet = TRUE) :
  InternetOpenUrl failed:

我该如何解决？

Answer 1

尝试以下任何一种方法：

编辑：将https更改为http

install.packages("http://cran.r-project.org/src/contrib/caret_6.0-80.tar.gz",
                 repos=NULL, method="libcurl")

要么

library(devtools)
install_url("http://cran.r-project.org/src/contrib/caret_6.0-80.tar.gz")