Iterating over a large unicode list taking a long time? - list

Question

I'm working with the program Autodesk Maya.
I've made a naming convention script that will name each item in a certain convention accordingly. However I have it list every time in the scene, then check if the chosen name matches any current name in the scene, and then I have it rename it and recheck once more through the scene if there is a duplicate.
However, when i run the code, it can take as long as 30 seconds to a minute or more to run through it all. At first I had no idea what was making my code run slow, as it worked fine in a relatively low scene amount. But then when i put print statements in the check scene code, i saw that it was taking a long time to check through all the items in the scene, and check for duplicates.
The ls() command provides a unicode list of all the items in the scene. These items can be relatively large, up to a thousand or more if the scene has even a moderate amount of items, a normal scene would be several times larger than the testing scene i have at the moment (which has about 794 items in this list).
Is this supposed to take this long? Is the method i'm using to compare things inefficient? I'm not sure what to do here, the code is taking an excessive amount of time, i'm also wondering if it could be anything else in the code, but this seems like it might be it.
Here is some code below.
class Name(object):
"""A naming convention class that runs passed arguments through user
dictionary, and returns formatted string of users input naming convention.
"""
def __init__(self, user_conv):
self.user_conv = user_conv
# an example of a user convention is '${prefix}_${name}_${side}_${objtype}'
#staticmethod
def abbrev_lib(word):
# a dictionary of abbreviated words is here, takes in a string
# and returns an abbreviated string, if not found return given string
#staticmethod
def check_scene(name):
"""Checks entire scene for same name. If duplicate exists,
Keyword Arguments:
name -- (string) name of object to be checked
"""
scene = ls()
match = [x for x in scene if isinstance(x, collections.Iterable)
and (name in x)]
if not match:
return name
else:
return ''
def convert(self, prefix, name, side, objtype):
"""Converts given information about object into user specified convention.
Keyword Arguments:
prefix -- what is prefixed before the name
name -- name of the object or node
side -- what side the object is on, example 'left' or 'right'
obj_type -- the type of the object, example 'joint' or 'multiplyDivide'
"""
prefix = self.abbrev_lib(prefix)
name = self.abbrev_lib(name)
side = ''.join([self.abbrev_lib(x) for x in side])
objtype = self.abbrev_lib(objtype)
i = 02
checked = ''
subs = {'prefix': prefix, 'name': name, 'side':
side, 'objtype': objtype}
while self.checked == '':
newname = Template (self.user_conv.lower())
newname = newname.safe_substitute(**subs)
newname = newname.strip('_')
newname = newname.replace('__', '_')
checked = self.check_scene(newname)
if checked == '' and i < 100:
subs['objtype'] = '%s%s' %(objtype, i)
i+=1
else:
break
return checked

Answer 1

are you running this many times? You are potentially trolling a list of several hundred or a few thousand items for each iteration inside while self.checked =='', which would be a likely culprit. FWIW prints are also very slow in Maya, especially if you're printing a long list - so doing that many times will definitely be slow no matter what.
I'd try a couple of things to speed this up:
limit your searches to one type at a time - why troll through hundreds of random nodes if you only care about MultiplyDivide right now?
Use a set or a dictionary to search, rather than a list - sets and dictionaries use hashsets and are faster for lookups
If you're worried about maintining a naming convetion, definitely design it to be resistant to Maya's default behavior which is to append numeric suffixes to keep names unique. Any naming convention which doesn't support this will be a pain in the butt for all time, because you can't prevent Maya from doing this in the ordinary course of business. On the other hand if you use that for differntiating instances you don't need to do any uniquification at all - just use rename() on the object and capture the result. The weakness there is that Maya won't rename for global uniqueness, only local - so if you want to make unique node name for things that are not siblings you have to do it yourself.
Here's some cheapie code for finding unique node names:
def get_unique_scene_names (*nodeTypes):
if not nodeTypes:
nodeTypes = ('transform',)
results = {}
for longname in cmds.ls(type = nodeTypes, l=True):
shortname = longname.rpartition("|")[-1]
if not shortname in results:
results[shortname] = set()
results[shortname].add(longname)
return results
def add_unique_name(item, node_dict):
shortname = item.rpartition("|")[-1]
if shortname in node_dict:
node_dict[shortname].add(item)
else:
node_dict[shortname] = set([item])
def remove_unique_name(item, node_dict):
shortname = item.rpartition("|")[-1]
existing = node_dict.get(shortname, [])
if item in existing:
existing.remove(item)
def apply_convention(node, new_name, node_dict):
if not new_name in node_dict:
renamed_item = cmds.ls(cmds.rename(node, new_name), l=True)[0]
remove_unique_name(node, node_dict)
add_unique_name ( renamed_item, node_dict)
return renamed_item
else:
for n in range(99999):
possible_name = new_name + str(n + 1)
if not possible_name in node_dict:
renamed_item = cmds.ls(cmds.rename(node, possible_name), l=True)[0]
add_unique_name(renamed_item, node_dict)
return renamed_item
raise RuntimeError, "Too many duplicate names"
To use it on a particular node type, you just supply the right would-be name when calling apply_convention(). This would rename all the joints in the scene (naively!) to 'jnt_X' while keeping the suffixes unique. You'd do something smarter than that, like your original code did - this just makes sure that leaves are unique:
joint_names= get_unique_scene_names('joint')
existing = cmds.ls( type='joint', l = True)
existing .sort()
existing .reverse()
# do this to make sure it works from leaves backwards!
for item in existing :
apply_convention(item, 'jnt_', joint_names)
# check the uniqueness constraint by looking for how many items share a short name in the dict:
for d in joint_names:
print d, len (joint_names[d])
But, like i said, plan for those damn numeric suffixes, maya makes them all the time without asking for permission so you can't fight em :(

Answer 2

Instead of running ls for each and every name, you should run it once and store that result into a set (an unordered list - slightly faster). Then check against that when you run check_scene
def check_scene(self, name):
"""Checks entire scene for same name. If duplicate exists,
Keyword Arguments:
name -- (string) name of object to be checked
"""
if not hasattr(self, 'scene'):
self.scene = set(ls())
if name not in self.scene:
return name
else:
return ''