R, Rexcel, create macro that counts of words in and excel worksheet

Question

I have following macro with the use of Rexcel that doesn't work. I have a list of words in range A1:A2 (mydf) and i want to count the occurence of a specific word (hello) but following doesn't work well. Could someone help me understand?

Sub findwords()
Worksheets("Sheet1").Activate
rinterface.StartRServer
rinterface.PutDataframe "mydf", Range("Sheet1!A1:A200")
rinterface.RRun "a <- length(grep(hello, mydf))"
rinterface.PutArray "a", Range("Sheet1!B2:B50")

End Sub

Answer 1

Following code is the right answer :

Sub findwords()
  MsgBox "finding the word hello"
  Rinterface.StartRServer
  Rinterface.PutArray "mydf", Range("Sheet1!A1:A200")
  Rinterface.RRun "a <- length(grep('hello', mydf))"
  Rinterface.GetArray "a", Range("Sheet1!B1")
End Sub