Example 0. + and append do the same thing
In [1]: list1 = [1, 2, 3, 4]
In [2]: list1 = list1 + [5]
In [3]: print list1
[1, 2, 3, 4, 5]
In [4]: list2 = [1, 2, 3, 4]
In [5]: list2.append(5)
In [6]: print list2
[1, 2, 3, 4, 5]
Example 1. Difference 1
1 2 3 4 5 | def proc(mylist):
mylist.append(6)
def proc2(mylist):
mylist = mylist + [6]
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In [9]: print list1
[1, 2, 3, 4, 5]
In [10]: proc(list1)
In [11]: print list1
[1, 2, 3, 4, 5, 6]
In [12]: print list2
[1, 2, 3, 4, 5]
In [13]: proc2(list2)
In [14]: print list2
[1, 2, 3, 4, 5]
Example 2. Difference 2: append
In [15]: list2.append([7,8,9])
In [16]: list2
Out[16]: [1, 2, 3, 4, 5, 6, [7, 8, 9]]
Example 3. Difference 2: +
In [17]: list1 = list1 + [7,8,9]
In [18]: list1
Out[18]: [1, 2, 3, 4, 5, 7, 8, 9]
Example 4. += works the same as append I
1 2 3 4 5 6 | In [19]: list3 = [1,2,3,4]
In [20]: list3 += [5]
In [21]: list3
Out[21]: [1, 2, 3, 4, 5]
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Example 5. += works the same as append II
1 2 | def proc3(mylis):
mylist += [6]
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In [23]: print list3
[1, 2, 3, 4, 5]
In [24]: proc3(list3)
In [25]: print list3
[1, 2, 3, 4, 5, 6]
Example 6. += concatenates the lists
In [26]: list3 += [7,8,9]
In [27]: list3
Out[27]: [1, 2, 3, 4, 5, 6, 7, 8, 9]