How to use the switch statement in R functions

Question

I would like to use for my function in R  the statement switch   to trigger different computation according to the value of the function s argument   For instance  in Matlab you can do that by writing     switch AA          case  1            case  2            case  3          end   I found this post - switch   statement usage - that explain how to use switch  but not really helpful to me as I want to perform more sophisticated computation  matrix operations  and not a simple mean

User · Accepted Answer

Well  switch probably wasn t really meant to work like this  but you can   AA    foo  switch AA   foo       case  foo  here      print  foo      bar       case  bar  here      print  bar               print  default            each case is an expression - usually just a simple thing  but here I use a curly-block so that you can stuff whatever code you want in there

User · Answer

I hope this example helps   You ca use the curly braces to make sure you ve got everything enclosed in the switcher changer guy  sorry don t know the technical term but the term that precedes the   sign that changes what happens    I think of switch as a more controlled bunch of if       else    statements   Each time the switch function is the same but the command we supply changes   do this  lt -  T1   switch do this      T1  X  lt - t mtcars          colSums mtcars    X            T2  X  lt - colMeans mtcars          outer X  X             stop  Enter something that switches me                                                                do this  lt -  T2   switch do this      T1  X  lt - t mtcars          colSums mtcars    X            T2  X  lt - colMeans mtcars          outer X  X             stop  Enter something that switches me                                                               do this  lt -  T3   switch do this      T1  X  lt - t mtcars          colSums mtcars    X            T2  X  lt - colMeans mtcars          outer X  X             stop  Enter something that switches me        Here it is inside a function   FUN  lt - function df  do this       switch do this          T1  X  lt - t df              P  lt - colSums df    X                    T2  X  lt - colMeans df              P  lt - outer X  X                     stop  Enter something that switches me              return P     FUN mtcars   T1   FUN mtcars   T2   FUN mtcars   T3

User · Answer

those various ways of switch         by index switch 1   one    two       1   one      by index with complex expressions switch 2    one      two        1   two      by index with complex named expression switch 1  foo   one    bar   two        1   one      by name with complex named expression switch  bar   foo   one    bar   two        1   two

User · Answer

This is a more general answer to the missing  Select cond1  stmt1      else stmtelse  connstruction in R  It s a bit gassy  but it works an resembles the switch statement present in C  while  TRUE      if  is na val         val  lt -  NULL      break       if  inherits val   POSIXct      inherits val   POSIXt          val  lt - paste0       format val    Y- m- d  H  M  S             break       if  inherits val   Date          val  lt - paste0       format val    Y- m- d             break       if  is numeric val   break   val  lt - paste0      gsub            val          break

[r] How to use the switch statement in R functions?

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