sathya <linuxcraft@redspice.com> asked:

sathya <linuxcraft@redspice.com> asked:

...

I have a list to pass in as a parameter to dtml-in but before doing that I would like to eliminate duplicates form the list. ie in ['1','2','1'] I want to skip the duplicate 1. is there a zope hack for this or do I have to use an external method

This requires some Python expression trickery which can't (currently) be done within DTML (filter and map aren't available to DTML). You are probably better off using a PythonMethod for such logic. For grins, I used the Python interpreter to bang out the following Python expression:

filter( None, map( lambda i, d={}: ( i, None )[ d.has_key(i) or d.update( {i: 1} ) or 0 ] , foo ) )

This is too convoluted to use in production code (and it strips out 0 values, too) -- much better a nice, straightforward, "Pythonic" solution, a Python method 'uniq' taking a single argument, 'items':

d = {} for item in items: if not d.has_key( item ): d.update( { item: 1 } ) return d.keys()

Call from DTML:

<dtml-in "uniq( myItems )" sort> ... </dtml-in> -- ========================================================= Tres Seaver tseaver@digicool.com tseaver@palladion.com

You're uniq method is not as fast as it could be. The call to has_key is superfluous and the update call has to creates a dictionary which then gets thrown away. All you need to do is: def uniq2(items): d = {} for item in items: d[item]=1 return d.keys() This saves creating a dictionary, and having to hash the key twice for every item. It runs about 2-3 times faster test # list of 10000 random integers results show unique keys and time there is a small advantage to not being the first run for string keys bash-2.02$ python uniq.py Integer keys uniq1 6214 0.0955042775547 uniq2 6214 0.0308158706009 String keys 14650 words in file uniq1 3521 0.0922106302846 uniq2 3521 0.036688347093 Second time around is a bit faster uniq1 3521 0.088270029681 uniq2 3521 0.036336634824 test code specify a text file to read into list of words =========== import time import whrandom import string def uniq1(items): d = {} for item in items: if not d.has_key( item ): d.update( { item: 1 } ) return d.keys() def uniq2(items): d = {} for item in items: d[item]=1 return d.keys() generator = whrandom.whrandom() # get some text file this is a zope mailing list file of about 90K listofwords = string.split(open('c:/temp/message.txt').read()) listofitems = [] for item in range(10000): listofitems.append(generator.randint(0,9500)) print 'Integer keys' starttime = time.clock() starttime = time.clock() l = uniq1(listofitems) stoptime = time.clock() print 'uniq1', len(l), stoptime-starttime l = uniq2(listofitems) stoptime = time.clock() print 'uniq2', len(l), stoptime-starttime print print 'String keys' print len(listofwords), 'words in file' starttime = time.clock() l = uniq1(listofwords) stoptime = time.clock() print 'uniq1', len(l), stoptime-starttime starttime = time.clock() l = uniq2(listofwords) stoptime = time.clock() print 'uniq2', len(l), stoptime-starttime print 'Second time around is a bit faster' starttime = time.clock() l = uniq1(listofwords) stoptime = time.clock() print 'uniq1', len(l), stoptime-starttime starttime = time.clock() l = uniq2(listofwords) stoptime = time.clock() print 'uniq2', len(l), stoptime-starttime