Writing a program converts guitar tabs to notes

Question

I am trying to learn what notes are where on the guitar, so I want to be able to type in what the string is tuned to and what fret I am playing and have the program tell me what note it is or type in the note and get back all the different places I can play it.

So far, I have a program that tells me what the note is based on the string and fret but I just wrote it the long way and it takes a lot of processing power. Based on what the user types in for what the string is tuned to, it opens a function for that string which asks what fret is being used, then based on the fret it runs one of the many elifs that I individually typed out.

For example:

elif fret == '3':
    print('That note is E')

I know there's a way to do it with not nearly as much code, but I'm really new to programming clearly and can't quite come up with the logic.

The canonical replacement for lots of `elif`s is a [`dict`](https://docs.python.org/2/tutorial/datastructures.html#dictionaries) e.g. `{'3': 'E', ...}`. — jonrsharpe, Nov 19 '14 at 22:21
As others have hinted at, you're trying to solve a "data question" with a "programming answer"... Since D strings and F-sharps won't change anytime soon, you can pre-calculate the answers to _all_ possible questions and save them in a data structure (bgporter's pair of `dict`s) or a file (probably `notes.json` or something). Then the only _programming_ part of the job is taking user questions, looking up the pre-calculated answer, and spitting it out. Much easier. — Kevin J. Chase, Nov 20 '14 at 00:06

score 4 · Accepted Answer · answered Nov 19 '14 at 22:38

Build a pair of dicts that map note names to pitch numbers and back, and you can build a simple function to do this, like:

NOTES = {"C" : 0, "C#" : 1,  "D": 2, "D#" : 3, "E": 4, "F": 5, 
   "F#" : 6, "G":  7, "G#" : 8, "A": 9, "A#" : 10, "B": 11}


NAMES = dict([(v, k) for (k, v) in NOTES.items()])


def GetNote(stringNote, fretNum):
   baseNote = NOTES[stringNote]
   fretNoteNum = (baseNote + fretNum) % 12
   return NAMES[fretNoteNum]

>>> GetNote("E", 0)
'E'
>>> GetNote("E", 1)
'F'
>>> GetNote("A", 7)
'E'
>>> GetNote("G", 6)
'C#'

Writing a program converts guitar tabs to notes

1 Answers1