qc: Create vector of characters from unquoted strings (variable names)
qc It is often needed to address variables in the data.frame in the such
manner: dfs[ , c("var1", "var2", "var3")]. qc ("quoted c") is a
shortcut for the such cases to reduce keystrokes. With qc you can write:
dfs[ , qc(var1, var2, var3)].
qe returns list of expression.
Vector of characters or expressions
unquoted names of variables in
qc or unquoted expressions in qe.