It requires that more than 3 vertices are selected. The weight of the middle vertices will be blended with either linear or quadratic interpolation with the vertex pair with the greatest distance as the blend sources. Select vertices and run 'blendWeightsByDistance' command.

Parameters:

• uvspace [uv] (default is False)
• quadraticblend [qb] (default is False)

Example:

import maya.cmds as mc
mc.blendWeightsByDistance()   # blends in linear 3d space
mc.blendWeightsByDistance(uv=True)  # blend in linear uv space
mc.blendWeightsByDistance(qb=True)  # blends in quadratic 3d space
mc.blendWeightsByDistance(uv=True, qb=True)  # blends in quadratic uv space