Mac安装R后出现You're using a non-UTF8 locale, therefore only ASCII characters will work.

1. Open Terminal

2. Write or paste in: defaults write org.R-project.R force.LANG en_US.UTF-8

3. Close Terminal

4. Start R

https://stackoverflow.com/questions/9689104/installing-r-on-mac-warning-messages-setting-lc-ctype-failed-using-c