head and tail for strings
The functions head and tail are very useful for working with lists, tables, data frames and even functions.But they do not work on strings. It is easy to define such functions__ strtail + if(n+ substring(s,1-n) + else + substring(s,nchar(s)-n+1)+ }__ strhead + if(n+ substr(s,1,nchar(... [Read more...]