RoboFont script to split glyphs from a kern group, but keep kerning (so you can fix it without disrupting it too much)

split-kerning-group-allfonts.py

"""
    Split glyphs from a given kerning group, but keep kerning 
    so you don’t lose a bunch of almost-correct kerns.
    
    (Slightly 
    
    E.g. If you need to split "e" glyphs out of the "o" group.
        
    USAGE:
        - set originalGroupName (group to split from)
        - set newGroupName (new group to make)
        - set names of glyphs to split out as a space-seperated list. 
          (Option + Command + C to copy these from font view.)
          
    Will run on all open fonts.

    Assumes kerning groups are named in conventional way, i.e. "public.kern1.glyphName" for left side of kern pair.
"""

# ---------------------------------------
# CONFIGURATION BELOW

originalGroupName = "public.kern2.o"
newGroupName = "public.kern2.c"

newGroupGlyphs = "c ccedilla cacute ccaron"


# CONFIGURATION ABOVE
# ---------------------------------------

def splitGroups(font):

    # make originalGroupName without newGroupGlyphNames
    cleanedOrginalGroup = [gname for gname in font.groups[originalGroupName] if gname not in newGroupGlyphs.split()]

    # update groups from new group info
    font.groups.update({originalGroupName: cleanedOrginalGroup, newGroupName: newGroupGlyphs.split()})

    # copy kerning for originalGroupName
    for (left, right), value in font.kerning.items():
        if originalGroupName.split(".")[1] == "kern1":
            if left == originalGroupName:
                font.kerning[newGroupName, right] = value
        if originalGroupName.split(".")[1] == "kern2":
            if right == originalGroupName:
                font.kerning[left, newGroupName] = value

for font in AllFonts():
    splitGroups(font)
    font.save()