"Stringizing" a list

[Mike Fletcher]

Something like
	string.join(hyperCollapse( data))

Should be fairly fast and general.

Enjoy,
Mike


import copy, types, sys
from types import ListType, TupleType # this now only supports the obsolete
stuff...

def hyperCollapse( inlist, allowedmap, type=type, list=list,
itype=types.InstanceType, maxint= sys.maxint):
	'''
	Destructively flatten a mixed hierarchy to a single level.
	Non-recursive, many speedups and obfuscations by Tim Peters :)
	'''
	try:
		# for every possible index
		for ind in xrange( maxint):
			# while that index currently holds a list
			expandable = 1
			while expandable:
				expandable = 0
				if allowedmap.has_key( type(inlist[ind]) ):
					# expand that list into the index
(and subsequent indicies)
					inlist[ind:ind+1] = list(
inlist[ind])
					expandable = 1
				
				# alternately you could iterate through
checking for isinstance on all possible
				# classes, but that would be very slow
				elif type( inlist[ind] ) is itype and
allowedmap.has_key( inlist[ind].__class__ ):
					# here figure out some way to
generically expand that doesn't risk
					# infinite loops...
					templist = []
					for x in inlist[ind]:
						templist.append( x)
					inlist[ind:ind+1] = templist
					expandable = 1
	except IndexError:
		pass
	return inlist

-----Original Message-----
From: cg at gaia.cdg.acriter.nl [mailto:cg at gaia.cdg.acriter.nl]
Sent: Wednesday, August 09, 2000 5:42 AM
To: python-list at python.org
Subject: "Stringizing" a list


I'm sure I've seen a place with a snippet for this, but I couldn't find it:

what's the cleanest way to convert a random nested list structure like:

['foo', ['bar', 'baz'], 'quux']

into:

'foo bar baz quux' ?

I've, ahem, solved this with a bit of recursion and relying on '+' to throw
in certain circumstances, but it's a hairy and ugly piece of code. 

-- 
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