caret包安装失败出现stringi问题版本R-3.5.0.tar.gz
请问这个问题怎么办？版本R-3.5.0.tar.gz
installing the source package ‘stringi’
trying URL 'http://cran.rstudio.com/src/contrib/stringi_1.2.2.tar.gz'
Content type 'application/x-gzip' length 7270627 bytes (6.9 MB)
downloaded 6.9 MB
* installing *source* package 'stringi' ...
** 成功将'stringi'程序包解包并MD5和检查
Warning in system("sh ./configure.win") : 'sh' not found
ERROR: configuration failed for package 'stringi'
* removing 'D:/program files/R language/R-3.5.0/library/stringi'
In R CMD INSTALL
Warning in install.packages :
installation of package ‘stringi’ had non-zero exit status
The downloaded source packages are in
‘C:\Users\Michael\AppData\Local\Temp\RtmpQXf6bD\downloaded_packages’
