Charles questions

Charles answers

• Use aggregate with a function that uses data from two columns (e.g. cov or prod)
• Y axis out of plotting region with barplot() in R
• adding a column based on other values
• Is there a way for an R function to tell if it's being called from a `for` or `while` loop?
• Optimal method of comparing a vector of numbers to values in another vector
• Prevent names in dataframe list from disappearing
• Re-inserting NAs into a vector
• convert a vector to a list
• Fastest Tall-Wide pivoting in R
• Order data frame by two columns in R