phonenumber

Background

When I recently posted some of my Turbo Pascal Stuff, I found an incomplete program that was supposed to do this. I was active on BBSes and, though I don’t recall the reason, I wanted a way to determine the possible words spelled by the BBS phone numbers (and/or how to determine what phone numbers correspond to words/phrases). I never got around to finishing the second part (numbers to letters) in Turbo Pascal, though.

I decided to create this functionality in R for three reasons:

1. to see if I could write the functions
2. to learn to publish a package to CRAN
3. to serve as a possible pedagogical example for others as it involves working with lists, splitting strings, and the expand.grid function.

phonenumber’s functions

• letterToNumber
• numberToLetter

Telephone keypad

For purposes of this package, the mapping of numbers to letters on a telephone’s keypad are as follows:

• Default behavior - if parameter qz is omitted (or has a value other than 0):
  • 2 corresponds to A, B, C
  • 3 corresponds to D, E, F
  • 4 corresponds to G, H, I
  • 5 corresponds to J, K, L
  • 6 corresponds to M, N, O
  • 7 corresponds to P, Q, R, S
  • 8 corresponds to T, U, V
  • 9 corresponds to W, X, Y, Z
  • 0 and 1 have no corresponding letters
• Alternate behavior - if parameter qz = 0:
  • 2 corresponds to A, B, C
  • 3 corresponds to D, E, F
  • 4 corresponds to G, H, I
  • 5 corresponds to J, K, L
  • 6 corresponds to M, N, O
  • 7 corresponds to P, R, S
  • 8 corresponds to T, U, V
  • 9 corresponds to W, X, Y
  • 0 corresponds to Q, Z
  • 1 has no corresponding letters