What's The Difference Between Plus And Append In Python For List Manipulation?

Possible Duplicate: Python append() vs. + operator on lists, why do these give different results? What is the actual difference between '+' and 'append' for list manipulation in

Solution 1:

There are two major differences. The first is that + is closer in meaning to extend than to append:

>>>a = [1, 2, 3]>>>a + 4
Traceback (most recent call last):
  File "<pyshell#13>", line 1, in <module>
    a + 4
TypeError: can only concatenate list (not "int") to list
>>>a + [4]
[1, 2, 3, 4]
>>>a.append([4])>>>a
[1, 2, 3, [4]]
>>>a.extend([4])>>>a
[1, 2, 3, [4], 4]

The other, more prominent, difference is that the methods work in-place: extend is actually like += - in fact, it has exactly the same behavior as += except that it can accept any iterable, while += can only take another list.

Solution 2:

Using list.append modifies the list in place - its result is None. Using + creates a new list.

Solution 3:

>>>L1 = [1,2,3]>>>L2 = [97,98,99]>>>>>># Mutate L1 by appending more values:>>>L1.append(4)>>>L1
[1, 2, 3, 4]
>>>>>># Create a new list by adding L1 and L2 together>>>L1 + L2
[1, 2, 3, 4, 97, 98, 99]
>>># L1 and L2 are unchanged>>>L1
[1, 2, 3, 4]
>>>L2
[97, 98, 99]
>>>>>># Mutate L2 by adding new values to it:>>>L2 += [999]>>>L2
[97, 98, 99, 999]

Solution 4:

+ is a binary operator that produces a new list resulting from a concatenation of two operand lists. append is an instance method that appends a single element to an existing list.

P.S. Did you mean extend?

Solution 5:

The + operation adds the array elements to the original array. The array.append operation inserts the array (or any object) into the end of the original array.

[1, 2, 3] + [4, 5, 6] // [1, 2, 3, 4, 5, 6]

b = [1, 2, 3]
b.append([4, 5, 6]) // [1, 2, 3, [4, 5, 6]]

Take a look here: Python append() vs. + operator on lists, why do these give different results?