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Use the extend() Method to Append a List Into Another List in Python. Python has a built-in method for lists named extend() that accepts an iterable as a parameter and adds it into the last position of the current iterable. Using it for lists will append the list parameter after the last element of the main list.
You can use the insert() method to insert an item to a list at a specified index. Each item in a list has an index. The first item has an index of zero (0), the second has an index of one (1), and so on.
Do you mean append?
>>> x = [1,2,3]
>>> y = [4,5,6]
>>> x.append(y)
>>> x
[1, 2, 3, [4, 5, 6]]
Or merge?
>>> x = [1,2,3]
>>> y = [4,5,6]
>>> x + y
[1, 2, 3, 4, 5, 6]
>>> x.extend(y)
>>> x
[1, 2, 3, 4, 5, 6]
The question does not make clear what exactly you want to achieve.
List has the append method, which appends its argument to the list:
>>> list_one = [1,2,3]
>>> list_two = [4,5,6]
>>> list_one.append(list_two)
>>> list_one
[1, 2, 3, [4, 5, 6]]
There's also the extend method, which appends items from the list you pass as an argument:
>>> list_one = [1,2,3]
>>> list_two = [4,5,6]
>>> list_one.extend(list_two)
>>> list_one
[1, 2, 3, 4, 5, 6]
And of course, there's the insert method which acts similarly to append but allows you to specify the insertion point:
>>> list_one.insert(2, list_two)
>>> list_one
[1, 2, [4, 5, 6], 3, 4, 5, 6]
To extend a list at a specific insertion point you can use list slicing (thanks, @florisla):
>>> l = [1, 2, 3, 4, 5]
>>> l[2:2] = ['a', 'b', 'c']
>>> l
[1, 2, 'a', 'b', 'c', 3, 4, 5]
List slicing is quite flexible as it allows to replace a range of entries in a list with a range of entries from another list:
>>> l = [1, 2, 3, 4, 5]
>>> l[2:4] = ['a', 'b', 'c'][1:3]
>>> l
[1, 2, 'b', 'c', 5]
foo = [1, 2, 3]
bar = [4, 5, 6]
foo.append(bar) --> [1, 2, 3, [4, 5, 6]]
foo.extend(bar) --> [1, 2, 3, 4, 5, 6]
http://docs.python.org/tutorial/datastructures.html
You can also just do...
x += y
If you want to add the elements in a list (list2) to the end of other list (list), then you can use the list extend method
list = [1, 2, 3]
list2 = [4, 5, 6]
list.extend(list2)
print list
[1, 2, 3, 4, 5, 6]
Or if you want to concatenate two list then you can use + sign
list3 = list + list2
print list3
[1, 2, 3, 4, 5, 6]
If we just do x.append(y), y gets referenced into x such that any changes made to y will affect appended x as well. So if we need to insert only elements, we should do following:
x = [1,2,3]
y = [4,5,6]
x.append(y[:])
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