Python - Append to a copy variable

Question

I've a list. I make the copy of that list. Now I want to append a number into its copy not into the original list. How would I do that?

a = [1,2,3]
b = a
b.append(4)

print a,b # prints [1, 2, 3, 4] [1, 2, 3, 4]

I want [1, 2, 3] [1, 2, 3, 4]. How would I do that?

@behzad.nouri, It's only available in Python 3.3+, OP is using Python 2.x. (using `print` statement) — falsetru, Aug 05 '14 at 11:41
Did you attempt to search for, e.g., "python copy list"? Gives excellent results. — , Aug 05 '14 at 11:48
python 2.x has module `copy`; with which you can `b = copy.copy(a)`; in addition you can always copy the elements of the list `b = a[:]` rather than a reference to the list itself. — Dima Tisnek, Aug 05 '14 at 12:49

score 2 · Accepted Answer · answered Aug 05 '14 at 11:40

2

to copy the values, you should use

import copy
a = [1,2,3]
b = copy.copy(a)
b.append(4)

print a,b

answered Aug 05 '14 at 11:40

Selva

1

@user1162512 If this answer helped you, please give it a +1 and accept it. – Aug 05 '14 at 11:44
2

Easier to use `b = a[:]` to make a copy. No need to `import copy` (but no harm done this way either). – Aug 05 '14 at 11:46

score 0 · Answer 2 · answered Aug 05 '14 at 12:15

0

Its easier to use b = a[:] to copy a list.

answered Aug 05 '14 at 12:15

Neerav Kumar

2 Answers2