get nearest neighbours of a vertex

Coding Python Support
1

Does the 2.5 API provide a way to get a list of a vertex’s nearest neighbours ? Blender has the required functionality (proportional edit moves nearest neighbours). I don’t want to program the tree if there’s an existing way through the API.

2

One possibility to write a def:
Select your vertex (vertices) let Blender select the nearest ones and check
compute the difference of vertices with select = True ?!

Try this:
make a object with several vertices … and let it be in edit-mode:

import bpy
    
def selectVertices(vertList):
 #   if bpy.context.area.type != 'VIEW_3D':
 #       bpy.context.area.type = 'VIEW_3D' 
       
    bpy.ops.mesh.select_all(action='DESELECT')
    bpy.ops.object.mode_set(mode='OBJECT')   
    obj = bpy.context.active_object.data.vertices 
    for i in vertList:
        print(i)
        obj[i].select = True   
    bpy.ops.object.editmode_toggle() #edit mode!   

print("
========")
vlist = [1,2,3] #e.g.
selectVertices(vlist)

def neighbours(vlist):
#    if bpy.context.area.type != 'VIEW_3D':
#        bpy.context.area.type = 'VIEW_3D'
    bpy.ops.object.mode_set(mode='EDIT')   
    bpy.ops.mesh.select_more()
    bpy.ops.object.mode_set(mode='OBJECT')   
    obj = bpy.context.active_object.data.vertices 
    res = []
    for el in obj:
   #     print(el.select)
        if el.select == True and not el.index in vlist:
           print(el)  
           res.append(el.index)
    bpy.ops.object.mode_set(mode='EDIT')               
    return res

print(neighbours(vlist))