Fits an object to the size of a group/objects world bounding box (used for 3d Projections and Planar Mapping)

fit_to_group_bbox.py

import maya.cmds as cmds

def fit_to_group_bbox(obj, group):
        '''Used to scale and translate a 3d projection node used for planar 
    mapping onto the size of a group or object. I haven't found any
    other use for it as of yet, but I have kept the variables open 
    in-case someone does.
    
    obj       : is the name of the object or projection you want to 
                resize
    group     : is the name of the object or group (usually Shading 
                Group) from which the bounding box will be retrieved and 
                that will be used to fit to.
    On Exit   : the "obj" is resized to the exact world bounding box of 
                "group"
    '''
    bbox = cmds.exactWorldBoundingBox(group)
    scl = []
    trn = []
    for i in range(3):
      scl.append(float( (bbox[i+3] - bbox[i]) ) / 2)
      trn.append(float( (bbox[i+3] + bbox[i]) ) / 2)
    cmds.setAttr(*['%s.scale' % obj]+scl, type='double3')
    cmds.setAttr(*['%s.translate' % obj]+trn, type='double3')