equal-tempered chord scales

computing the members of each of the chords in a chord scale in a particular key (a python script)

# takes one argument: an integer representing the position in
# the set of keys (beginning with 'A')

# key   number
# A     0
# Bb    1
# B     2
# C     3
# C#    4
# D     5
# Eb    6
# E     7
# F     8
# F#    9
# G    10
# Ab   11

import sys

# the key the user requested on the command line
requested_key = int(sys.argv[1])

# the set of keys (equivalent to the chromatic scale)
# (two octaves used to make the script smaller)

key_set = ('A', 'Bb', 'B', 'C', 'C#', 'D', 'Eb', 'E', 'F', 'F#', 'G', 'Ab', 'A', 'Bb', 'B', 'C', 'C#', 'D', 'Eb', 'E', 'F', 'F#', 'G', 'Ab')

# the intervals (the spacing) in the diatonic scale
# (interval = number of steps in the chromatic scale from one step to another step)

diatonic_scale_intervals_set = (2, 2, 1, 2, 2, 2, 1)

chord_scale_qualities = ('', 'minor', 'minor', '', '', 'minor', 'diminished')

cur_key_set_position = requested_key

steps_in_current_key = []

print "current key: %s" %key_set[cur_key_set_position]

print "scale steps in current key: ",
steps_in_current_key.append(key_set[cur_key_set_position] )

for interval in diatonic_scale_intervals_set:
    cur_key_set_position = cur_key_set_position + interval
    steps_in_current_key.append( key_set[cur_key_set_position] )

for step in steps_in_current_key:
    print step,
print
print

print "current key's chord scale: ",
for i in range(0,6):
    if i in [1,2,5]:
        print "%s minor" % steps_in_current_key[i],
    else:
        print steps_in_current_key[i],
print
print

print 'use the number of the key to tell this script what key you want'