Python list insert in last

How to insert item last in list python

How to Create a List in Python To create a list in Python, we use square brackets. How Do You Add an Item to a List in Python? There are three methods we can use when adding an item to a list in Python.

Python List insert() – How to Add to a List in Python

The list data type is one of the built-in data structures in Python along with sets, tuples, and dictionaries. You use a list to organize, group, and store data.

But each of these data structures has distinctive features that differentiates them from each other.

In this article, we’ll see how to create a list in python. We’ll also see how to add items to a list using the insert() , append() , and extend() methods.

How to Create a List in Python

To create a list in Python, we use square brackets. Here’s an example:

myList = ['one', 'two', 'three'] print(myList) # ['one', 'two', 'three']

In the code above, we created a list called myList with three items – «one», «two», and «three». As you can see above, the items are in the square brackets.

How Do You Add an Item to a List in Python?

There are three methods we can use when adding an item to a list in python. They are: insert() , append() , and extend() . We’ll break them down into separate sub-sections.

How to Add an Item to a List Using the insert() Method

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.

Here’s an example using the insert() method:

myList = ['one', 'two', 'three'] myList.insert(0, 'zero') print(myList) # ['zero', 'one', 'two', 'three']

In the example above, we created a list with three items: [‘one’, ‘two’, ‘three’] .

We then used the insert() method to insert a new item – «zero» at index 0 (the first index): myList.insert(0, ‘zero’) .

The insert() method takes in two parameters – the index of the new item to be inserted and the value of the item.

How to Add an Item to a List Using the append() Method

Unlike the insert() method which allows us to specify where to insert an item, the append() method adds the item to the end of the list. The new item’s value is passed in as a parameter in the append() method.

myList = ['one', 'two', 'three'] myList.append('four') print(myList) # ['one', 'two', 'three', 'four']

The new item was passed in as a parameter in the code above: myList.append(‘four’) .

When printed to the console, we have the item at the last index of the list.

How to Add an Item to a List Using the extend() Method

You can use the extend() method to append a data collection to a list. I’m using «data collection» here because we can also append sets, tuples, and so on to a list.

How to Append a List to a List Using the extend() Method

myList1 = ['one', 'two', 'three'] myList2 = ['four', 'five', 'six']

In the code above, we created two lists – myList1 and myList2 . Next, we’ll append the items in the second list to the first one.

So when we print myList1 , we’ll have this: [‘one’, ‘two’, ‘three’, ‘four’, ‘five’, ‘six’] .

Here’s everything put together:

myList1 = ['one', 'two', 'three'] myList2 = ['four', 'five', 'six'] myList1.extend(myList2) print(myList1) # ['one', 'two', 'three', 'four', 'five', 'six']

How to Append a Tuple to a List Using the extend() Method

The process here is the same as the last example, except that we’re appending a tuple. You create a tuple using parentheses.

Let’s append a tuple to a list using the extend() method.

myList1 = ['one', 'two', 'three'] myList2 = ('four', 'five', 'six') myList1.extend(myList2) print(myList1) # ['one', 'two', 'three', 'four', 'five', 'six']

We get the same result as in the last section.

Conclusion

In this article, we talked about lists in Python.

We saw how to create a list and the various methods for adding items to a list.

We added items to our list using the insert() , append() , and extend() methods.

The insert() method inserts a new item in a specified index, the append() method adds a new at the last index of a list, while the extend() method appends a new data collection to a list.

Python — Add List Items, W3Schools offers free online tutorials, references and exercises in all the major languages of the web. Covering popular subjects like HTML, CSS, JavaScript, Python, SQL, Java, and many, many more.

How to put first element in list to last place, python

There’s more than one way to do it. this one edits the list in place (meaning all references to the ‘men’ list see the change):

>>> men = [168, 172, 181, 166, 172, 174, 165, 169, 169, 185] >>> men.append(men.pop(0)) >>> men [172, 181, 166, 172, 174, 165, 169, 169, 185, 168] 

Is what I would do. This slices the list such that you have everything but the first element, then adds that onto the end.

This returns [172, 181, 166, 172, 174, 165, 169, 169, 185, 168] when applied to the initial value of men , as an example.

Your question is still not clear now. May you wanna do a comparision of men values with each value of women.

for m in men: biggest_abs = 0 for w in women: a = abs(m-w) if biggest_abs < a: biggest_abs = a print("biggest_abs is ", biggest_abs) 

This will print intermediate steps:

('biggest_abs is ', 18) ('biggest_abs is ', 22) ('biggest_abs is ', 31) ('biggest_abs is ', 16) ('biggest_abs is ', 22) ('biggest_abs is ', 24) ('biggest_abs is ', 15) ('biggest_abs is ', 19) ('biggest_abs is ', 19) ('biggest_abs is ', 35) 

biggest_abs = 0 for m in men: for w in women: a = abs(m-w) if biggest_abs < a: biggest_abs = a print("biggest_abs is ", biggest_abs) ('biggest_abs is ', 35) 

For the smallest difference just switch geater to smaller than in the if condition and give the value a meaningful name.

How to add an item at the last nested list of an outer list, Add a comment. 1. If you need a general solution try this: def last_inner_append (x, y): try: if isinstance (x [-1], list): last_inner_append (x [-1], y) return x except IndexError: pass x.append (y) return x >>> x = [1,2, [3,4, [5,6]]] >>> y = 7 >>> last_inner_append (x, y) [1,2, [3,4, [5,6,7]]] It recursively works through the …

Add first and last number of a list

You need to check if your list is empty or not.

def addFirstAndLast(x): return (x[0] + x[-1]) if x else 0 

The last test case passes an empty list. An empty list has neither [0] nor [-1] elements.

Of course, in your 3rd case there are no items, hence no relevant index.

Insert element in Python list after every nth element, It ends up with a list with each element being a single character (splitting strings). i = n while i < len (letters): letters.insert (i, 'x') i += (n+1) where n is after how many elements you want to insert 'x'. This works by initializing a variable i and setting it equal to n.

Python - Add List Items

Append Items

To add an item to the end of the list, use the append() method:

Example

Using the append() method to append an item:

Insert Items

To insert a list item at a specified index, use the insert() method.

The insert() method inserts an item at the specified index:

Example

Insert an item as the second position:

Note: As a result of the examples above, the lists will now contain 4 items.

Extend List

To append elements from another list to the current list, use the extend() method.

Example

Add the elements of tropical to thislist :

thislist = ["apple", "banana", "cherry"]
tropical = ["mango", "pineapple", "papaya"]
thislist.extend(tropical)
print(thislist)

The elements will be added to the end of the list.

Add Any Iterable

The extend() method does not have to append lists , you can add any iterable object (tuples, sets, dictionaries etc.).

Example

Add elements of a tuple to a list:

thislist = ["apple", "banana", "cherry"]
thistuple = ("kiwi", "orange")
thislist.extend(thistuple)
print(thislist)

Print the last three items of a list in Python, The other issue is that, even reversing those two indexes and using pizzas[-3:-1], ending at -1 will actually not include the last item. The start index is "inclusive", while end is "exclusive." Fortunately, Python has a shorthand for going up until the very end of the list, which is simply to omit the end argument when slicing.

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Python | Move element to end of the list

The manipulation of lists is quite common in day-day programming. One can come across various issues where one wishes to perform using just one-liners. One such problem can be of moving a list element to the rear ( end of list ). Let’s discuss certain ways in which this can be done.

Method #1 : Using append() + pop() + index()
This particular functionality can be performed in one line by combining these functions. The append function adds the element removed by pop function using the index provided by index function.

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The original list is : ['3', '5', '7', '9', '11'] The modified element moved list is : ['3', '7', '9', '11', '5']

Time Complexity: O(n), where n is the length of the list test_list
Auxiliary Space: O(n) additional space of size n is created where n is the number of elements in the res list

Method #2: Using sort() + key = (__eq__)
The sort method can also be used to achieve this particular task in which we provide the key as equal to the string we wish to shift so that it is moved to the end.

Python3

The original list is : ['3', '5', '7', '9', '11'] The modified element moved list is : ['3', '7', '9', '11', '5']

Method #3 : Using remove() and insert() methods

Python3

The original list is : ['3', '5', '7', '9', '11'] The modified element moved list is : ['3', '7', '9', '11', '5']

Method #4 : Using list comprehension

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Method #4 : Using del and ‘+’ operator

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Step-by-step algorithm:

1. Initialize the list test_list with the given input.
2. Assign the value element to the variable element.
3. Use the index() method to find the index of the element in the list that matches element. Assign the resulting index to the variable i.
4. Use the del keyword to remove the element at the index i from the list.
5. Use concatenation to add the updated element to the list.
6. Assign the updated list to the variable test_list.
7. Print the updated list.

Time complexity:
The time complexity of the algorithm is O(n), where n is the length of the input list test_list. The index() method has a linear time complexity with respect to the length of the list. The concatenation operation also has a linear time complexity with respect to the length of the list.

Auxiliary space complexity:
The auxiliary space complexity of the algorithm is O(1), constant. This is because the algorithm only creates a few variables to store the input list, the element to be updated, and the updated list. The size of these variables is independent of the size of the input list. Therefore, the space complexity of the algorithm is constant.

here’s an approach using collections.deque.rotate():

The collections.deque class in Python provides a rotate() method, which can be used to move elements in a list. We can convert our list into a deque, rotate it to move the desired element to the end, and then convert it back into a list.

Initialize the list and the element to be moved.
Convert the list to a deque using the collections.deque method.
Find the index of the element using the index() method.
Rotate the deque by the number of steps needed to move the element to the end using the rotate() method.
Convert the deque back to a list using the list() method.
Print the modified list.

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