Creates a ctrl at a selected joint

ctrlCreator.py

import maya.cmds as cmds

def getInheritedRotation(obj):
    
    rotation = [0,0,0]
    
    p = cmds.listRelatives(obj, allParents=True)
    
    while p != None:
        if cmds.nodeType(p) != "joint":
            rotation = [x + y for x,y in zip(rotation, cmds.xform(p, q=True, rotation=True))]
        else:
            rotation = [x + y for x,y in zip(rotation, cmds.joint(p, q=True, orientation=True))]
        p = cmds.listRelatives(p, allParents=True)
    
    return rotation
    
def getChildLevel(obj):
    p = cmds.listRelatives(obj, allParents=True, type="joint")
    level = 1
    while p != None:
        level += 1
        p = cmds.listRelatives(p, allParents=True, type="joint")
        
    return level
    
def generateColour(level, lenLevels, red=True, green=True, blue=False, redSub=False, greenSub=True, blueSub=False):
    div = 1.0/lenLevels
    col = [0,0,0]
    
    if red and not redSub:
        col[0] = div*level
    elif red:
        col[0] = 1-div*level
        
    if green and not greenSub:
        col[1] = div*level
    elif green:
        col[1] = 1-div*level
        
    if blue and not blueSub:
        col[2] = div*level
    if blue:
        col[2] = 1-div*level
        
    return col
    
    
def generateColourList(lenLevels, red=True, green=True, blue=False, redSub=False, greenSub=True, blueSub=False):
    colours = []
    
    for i in range(lenLevels):
        colours.append(generateColour(i, lenLevels, red, green, blue))
    
    return colours
    
if __name__ == "__main__":
    jnts = cmds.ls(selection=True, type="joint")
    
    colours = generateColourList(len(jnts))
    
    
    for i,jnt in enumerate(jnts):
        jntPos = cmds.joint(jnt, q=True, p=True)
        jntOri = cmds.joint(jnt, q=True, o=True)
        
        jntOri[1] += 90
        
        finalJntOri = [x + y for x,y in zip(jntOri, getInheritedRotation(jnt))]
        
        ctrl = cmds.circle(name="{}_ctrl".format(jnt))
        
        ctrl[1] = cmds.listRelatives(ctrl[0], shapes=True, type="nurbsCurve")[0]
        
        cmds.setAttr("{}.overrideEnabled".format(ctrl[1]), 1)
        cmds.setAttr("{}.overrideRGBColors".format(ctrl[1]), 1)
        cmds.setAttr("{}.overrideColorRGB".format(ctrl[1]), *colours[i], type="double3")
        
        
        cmds.xform(ctrl, translation=jntPos, rotation=finalJntOri)
        cmds.delete(ctrl, ch=True)