To determine if a file named thesis_data.csv exists in your working directory
you can use the code:
file.exists('thesis_data.csv')
This code returns TRUE if the files exists and FALSE if it does not.
if statement that loads the file using read.csv() only if the
file exists.else clause that prints “OMG MY THESIS DATA IS MISSING. NOOOO!!!!”
if the file doesn’t exist.