Tidyverse Packages

https://www.tidyverse.org/packages/

Advanced R

https://github.com/hadley/adv-r/ 

R for Data Science

https://r4ds.had.co.nz/   

Statistical Inference via Data Science A moderndive into R and the tidyverse

https://moderndive.com/ 

R tutorial site

https://data-flair.training/blogs/r-tutorials-home/ 

* Regular Expression 

grep 관련

https://www.rdocumentation.org/packages/base/versions/3.6.2/topics/grep?fbclid=IwAR3suZ9Q-ht8Fr1FIOTs4jFUxDrUUrz6D7l8pq5M_IWj92cykm6z00L_2So 

R regular Expression

http://www.endmemo.com/program/R/grep.php?fbclid=IwAR38BuPoAVbX4n6clGSAS4jFENcbgWATNQfcfMsiHjVS6BDt4wjQfxlKCT0

메모 → $: End of the string, ^: Beginning of the string