printing verts, face indices, and their normals

import bpy

current_obj = bpy.context.active_object

print("="*40) # printing marker
for polygon in current_obj.data.polygons:
    verts_in_face = polygon.vertices[:]
    print("face index", polygon.index)
    print("normal", polygon.normal)
    for vert in verts_in_face:
        print("vert", vert, " vert co", current_obj.data.vertices[vert].co)

printing verts and faces of object to a text file

Blender 2.5 Printing Edge Keys

quick example:

import bpy

for item in bpy.data.objects:
    if item.type == 'MESH':
        for e in item.data.edge_keys:
            print(e)

Blender 2.5 Python Find Connected Vertices

given a list of edges, how do you find what vertices are connected to a given vertex?

Edges = [   
                [0,1],[1,2],[2,3],[3,0],
                [4,5],[5,6],[6,7],[7,4],
                [0,4],[1,5],[2,6],[3,7]
            ]
numbered_vertex = 1   # where 1 is an arbitrary choice of vertex
for i in Edges:
    if numbered_vertex in i:
        print(i)

or this way..a little bit more confusing at first.. but ultimately not too unwieldy.

Edges = [   
                [0,1],[1,2],[2,3],[3,0],
                [4,5],[5,6],[6,7],[7,4],
                [0,4],[1,5],[2,6],[3,7]
            ]
n = 1   # where 1 is an arbitrary choice of vertex
print([x for x in Edges if x[0] == n or x[1] == n])
# or 
print([x for x in Edges if n in x])

Blender 2.5 Python Printing Groups and Objects and using Text Editor

# create a named text object 
>>> bpy.data.texts.new(name="dothistext")
bpy.data.texts["dothistext"]

py script to print names of groups in scene and their objects

import bpy

# print a divider
print("="*20)

for item in bpy.data.groups:
    print(item.name)
    for object in item.objects:
        print("--", object.name)

print() statements print to the debug console, if you don't know where that is. read this thread.
( Blender-2.57-User-preferences-and-the-console )

Useful for self when documenting what parts have been optimized manually. someone else might find a use for it. This script makes a textfile inside blender, which will be visible in the 'Text Editor' view.

import bpy
# creates a new text file, named "SceneList"
# writes Groups and contained Objects to it.

bpy.data.texts.new(name="SceneList")
newtext = bpy.data.texts["SceneList"] 
# or in one line
# newtext = bpy.data.texts.new(name="SceneList")

newtext.write("="*20 + "\n") # makes a divider

# your scene must contain groups. (groups are a collection of objects)
for item in bpy.data.groups:
    newtext.write(item.name + "\n")
    for object in item.objects:
        newtext.write("--" + object.name + "\n")

An example of reading a file from disk and writing it to a textobject:

# will create a text file called MyTextName (it will appear in the dropdown)
bpy.data.texts.new(name="MyTextName") 

# give give you a reference to that object, once created.
textobject = bpy.data.texts["MyTextName"] 

with open("yourtexttoread.txt", r) as readfile:
    for line in readfile:
        textobject.write(line)