[Tutor] Cloning lists to avoid alteration of original list

[Alistair McGowan]

Dear All,
		I am having problems with cloning a list in such a 
way that it alters one list but not the other. The list for the new 
area should have "4"

I have tried the standard procedure of taking a slice of the list, 
renaming it and operatiing on that, but to no avail. One issue that 
may make a difference is that I am taking a slice of a longer list, 
rather than the complete list.

Here is the section of code, which is a class. I have tried cloning 
the two lists outside of the class, as well as within the class, but 
the program always carries out the changes to both lists. I apologize 
for the length of the extact. If further information is needed, 
please let me know.
	Thanks in advance,
			Al

class mergeTaxa: # geodispersal of taxon lists from colliding areas
	def __init__(self,m,y,clone1,clone2):
		self.mergetaxa=[] #empty list
		self.mergetaxa.append (name)#id of new merged area
		one = clone1
		two = clone2
		print "one", one
		print "two", two
		temp = []# an empty list for listing taxa for comparison
		for e in range (0, len(one)):# starts to loop over 
list 1 and writes to merged list
			x = one[e] #extracts info for each taxon in area
			a = one[e][0]#gets the id #
			if one [e][2]==0: #checks if taxon is alive
				one[e][3]= 4
				print clone1
				self.mergetaxa.append(x)
				temp.append(a)
			else:
				pass
		for j in range (0, len(two)):# starts loop over other list
			p=two[j]
			f = two[j][0]
			if two[j][2]==0:
				z = temp.count(f)# checks if taxon 
occurs in other area list
				if z ==0: #  if not add to new area list
					two[j][3]=4
					self.mergetaxa.append(p)
				else:
					pass
			else:
				pass
		merge = self.mergetaxa
		print "merged", merge
		print clone1
		print clone2
		tbya.append(merge)#writes out to main taxon by area matrix
-- 
Alistair J. McGowan
Department of Earth Sciences,
University College, London,
London

WC1E 6BT

Phone: TBA
Fax: +44 (0)20 7387 1612

"Hope is a duty from which paleontologists are exempt."
				David Quammen

"Empty causes. You've got yours and I've got mine"
				Greg Graffin
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