Transpose by semitone?

[chrisspen]

Is there anyway to transpose by just a semitone and not an entire step?

Currently, calling up(1) on a C gives you a D and not a C#.

I tried calling up(0.5) but that seems to round up to up(1).

[lets00]

I've added support to transpose semitones. Now when you call

...
abc-transpose.up(abcfile, 1)

It will transpose 1 semitone. To transpose 1 tone, you must call up(2).

[chrisspen]

Awesome. Thanks.

[chrisspen]

Actually, I think this has introduced a bug.

For the abc:

X:1
M:C
K:A
L:1/8
c2 c2 d2 e2|e2 d2 c2 B2|A2 A2 B2 c2|c3 B B4

if I transpose this up(1), it changes the duration of several notes to:

X:1
M:C
K:A#
L:1/8
c^2 c^2 d^2 f2|f2 d^2 c^2 c2|A^2 A^2 c2 c^2|c^3 c c4

Notice the c2 notes are now c notes. I think you're trying to add the sharp ^ symbol to the note, but it has to go before the note letter, not between the note letter and duration number.

I'm not sure how this effects the key, but that also might be wrong. If I manually fix the sharp symbols, then I get:

X:1
M:C
K:A#
L:1/8
^c2 ^c2 ^d2 f2|f2 ^d2 ^c2 c2|^A2 ^A2 c2 ^c2|^c3 c c4

However, that doesn't sound right.

[lets00]

Hmm, I got confused and changed the sharp symbol after a note (when the correct is before). I'll fix it.

[Askaholic]

I'm not sure how this effects the key, but that also might be wrong. If I manually fix the sharp symbols, then I get:

X:1
M:C
K:A#
L:1/8
^c2 ^c2 ^d2 f2|f2 ^d2 ^c2 c2|^A2 ^A2 c2 ^c2|^c3 c c4

However, that doesn't sound right.

A# isn't really a key that you would naturally write in as it would require the key signature to have double sharps. What you would really expect is for the output to be in Bb. It should look like this:

X:1
M:C
K:Bb
L:1/8
d2 d2 e2 f2|f2 e2 d2 c2|B2 B2 c2 d2|d3 c c4

However, there are a few situations in which there is a choice of which key the output could reasonably be notated in. In particular for the keys of Cb/B, Gb/F#, and Db/C#.

An interface like this might work nicely:

abc-transpose.to_key(abcfile, "Bb")