If you just wanna see the final report and don't wanna knit it by yourself, just download this html(click and Ctrl+S, with your columbia gmail logged in):
https://drive.google.com/open?id=15pokdPPv8trdWEai-40uUwn2O34KDmJ2
Here are some solutions to some common problems when you try to run/knitr "wk2-Tutorial-TextMining.Rmd".
Hope it can help you.
During the first chunk of packages installation&loading, you may see several warnings(which doesn't matter) or errors(which prevents success install/load).
We suggest run "library("rvest"); library("tibble"); ..." line by line and figure out which packages haven't been properly installed. Then, install.package("<TheTroublePackageName>")
So you can manually look up the error messages in Google.
Sometimes it may already output the directions to solve the error, just follow it.