Sunday, March 3, 2024

Swap Perform in Python: 5 Most Pythonic Methods to Swap

A number of strategies can be found to implement a swap operate in Python, together with tuple task and XOR.

Tuple Task Swap Methodology

The tuple task methodology creates two tuples with two variables every. The primary tuple comprises the unique variables, whereas the second has their exchanged values. Lastly, these tuples are “unpacked” into particular person variables, successfully finishing the swap course of. This method means that you can swap values in a single assertion with no need a short lived variable.

For instance:

a, b = b, a

Whenever you execute a, b = b, a in Python, the next occurs:

  1. Tuple Packing: The precise-hand facet b, a creates a tuple with the present values of b and a. No precise tuple object is created in reminiscence; it’s only a conceptual packing.
  2. Worth Task: Python then unpacks the tuple into the variables on the left-hand facet within the order they’re listed. The primary ingredient of the tuple (the unique b) is assigned to a, and the second ingredient (the unique a) is assigned to b.
  3. Simultaneous Variable Replace: Each assignments occur nearly concurrently. There isn’t a intermediate state the place one variable has been modified however the different has not, which is why the swap can happen with out an extra momentary variable.

Python handles this operation elegantly and atomically, making certain that the variables are swapped with none want for a short lived storage location.

XOR Methodology for Swapping

The XOR methodology may be employed as one other technique to implement the swap operate. This methodology makes use of bitwise XOR operations to swap the values of two variables. Though barely extra advanced, the XOR methodology may be extra environment friendly in sure situations. To carry out a swap utilizing the XOR methodology, you need to use the next code:

a = a ^ b
b = a ^ b
a = a ^ b

This methodology works, for instance, when utilizing two integers:

a = 21
b = 42

a = a ^ b
b = a ^ b
a = a ^ b

# 42

# 21

This code snippet makes use of the XOR bitwise operator (^) to swap the values of two variables, a and b, with out utilizing a short lived variable.

To recap the XOR operator, be happy to observe my explainer video:

Right here’s what occurs intimately:

  1. a = a ^ b: The XOR operation is carried out between a (21) and b (42). The results of this operation is saved again in a. The property of XOR is that two similar bits lead to 0 and two completely different bits lead to 1. This successfully encodes the values of a and b into a.
  2. b = a ^ b: Now, the brand new worth of a is XORed with b. For the reason that present a comprises the encoded authentic values of a and b, this operation decodes the unique worth of a and assigns it to b.
  3. a = a ^ b: Lastly, the brand new a (which is the encoded authentic values) is XORed with the brand new b (which is now the unique worth of a). This decodes again to the unique worth of b and assigns it to a.

The XOR swap algorithm takes benefit of the truth that XORing a quantity with itself leads to zero, and XORing a quantity with zero leads to the unique quantity. This enables the unique values of a and b to be swapped with out the necessity for a short lived storage variable.

After this sequence of operations, a turns into 42 and b turns into 21, which is confirmed by the print statements.

String Swapping with Unpacking

The unpacking strategy is the underlying precept behind this easy swap operation in Python. It means that you can simply rearrange or trade the values of a number of variables concurrently (e.g., a, b, c = c, a, b). This makes it a strong and versatile methodology for managing information in your code.

This straightforward but efficient methodology allows you to swap values with out the necessity for any extra momentary variables or advanced procedures. It really works for any information sort, together with numbers and strings. As an example, let’s think about the next examples:

# Swapping numbers
x = 5
y = 10
x, y = y, x
print(x, y)  # Output: 10 5

# Swapping strings
str1 = "Good day"
str2 = "World"
str1, str2 = str2, str1
print(str1, str2)  # Output: World Good day

🧑‍💻 Advisable: Python Unpacking [Ultimate Guide]

Listing Swapping

One other state of affairs the place swapping is required entails lists. Suppose you’re working with an inventory in Python and have to trade the positions of two components. You should use the facility of tuple unpacking and listing indexing to realize this rapidly:

my_list = [23, 65, 19, 90]
pos1, pos2 = 0, 2
my_list[pos1], my_list[pos2] = my_list[pos2], my_list[pos1]

The given code snippet swaps the weather at positions pos1 and pos2 within the listing my_list.

Right here’s the method:

  • my_list begins as [23, 65, 19, 90].
  • pos1 is about to 0, and pos2 is about to 2, that means we’ll be swapping the weather on the first and third positions within the listing (indexing begins at 0 in Python).
  • The swap is finished in a Pythonic approach, just like the variable swap mentioned earlier: my_list[pos1], my_list[pos2] = my_list[pos2], my_list[pos1].
  • This line creates a tuple from the weather on the specified positions after which unpacks them again into the listing on the swapped positions.

After this line of code executes, the listing my_list is modified to [19, 65, 23, 90] as a result of the weather at indices 0 and 2 have been swapped.


[19, 65, 23, 90]

Tuple Swapping

In contrast to lists, tuples are immutable, which implies their values can’t be modified as soon as they’re created. Because of their immutability, you can not swap components instantly inside a tuple. As a substitute, you’ll be able to create a brand new tuple with the swapped components utilizing a mixture of indexing and tuple concatenation.

For instance:

original_tuple = (1, 2, 3, 4, 5)
index1, index2 = 1, 3

# Create a brand new tuple with swapped components
swapped_tuple = original_tuple[:index1] + (original_tuple[index2],) + original_tuple[index1+1:index2] + (original_tuple[index1],) + original_tuple[index2+1:]

print(swapped_tuple)  # Output: (1, 4, 3, 2, 5)

The code snippet demonstrates how one can swap components in a tuple, which is an immutable sequence in Python. Since tuples can’t be modified after creation, you will need to create a brand new tuple to characterize the swapped state. Right here’s how the swapping course of works within the given code:

  • original_tuple is outlined as (1, 2, 3, 4, 5).
  • index1 and index2 are set to 1 and 3, respectively, indicating the positions of components within the tuple that must be swapped (retaining in thoughts that Python makes use of 0-based indexing).

The swapped_tuple is constructed as follows:

  1. original_tuple[:index1]: Selects all components from the beginning of the tuple as much as however not together with the ingredient at index1. On this case, it’s (1,).
  2. (original_tuple[index2],): Creates a brand new tuple containing simply the ingredient at index2. The comma is important to point it’s a tuple with one ingredient: (4,).
  3. original_tuple[index1+1:index2]: Selects the weather between index1 and index2, not together with the ingredient at index2: (3,).
  4. (original_tuple[index1],): Just like step 2, this creates a tuple with the ingredient at index1: (2,).
  5. original_tuple[index2+1:]: Selects all the weather after index2 to the tip of the unique tuple: (5,).

These components are concatenated utilizing the + operator to kind swapped_tuple. Whenever you print swapped_tuple, the output is (1, 4, 3, 2, 5), exhibiting that the weather on the 1st index (2) and the third index (4) have been swapped.

Tuple Swapping Utilizing Listing Swapping

One other strategy to swapping components in tuples is changing the tuple to an inventory, performing the swap on the listing, after which changing the listing again to a tuple:

original_tuple = (1, 2, 3, 4, 5)
index1, index2 = 1, 3

# Convert tuple to listing
temp_list = listing(original_tuple)

# Swap components within the listing
temp_list[index1], temp_list[index2] = temp_list[index2], temp_list[index1]

# Convert listing again to tuple
swapped_tuple = tuple(temp_list)

print(swapped_tuple)  # Output: (1, 4, 3, 2, 5)

Generalized swap() Perform

In sure conditions, chances are you’ll have to swap variable values of various sorts utilizing the swap() operate. To perform this, you’ll be able to harness the pliability of Python’s built-in capabilities by making a customized swap operate:

def swap(x, y):
    return y, x

a="Good day"
b = 42
a, b = swap(a, b)

This practice operate takes two variables as enter and returns their swapped values. By using such a operate, you’ll be able to swap variables of any sort seamlessly.

A Few Phrases on These Momentary Variables

In lots of programming languages, together with Python, chances are you’ll have to swap the values of two variables. One widespread technique to obtain that is by utilizing a short lived variable. A short lived variable serves as a placeholder to retailer the unique worth of one of many variables earlier than reassigning its worth.

As an example, think about the next Python code which swaps the values of a and b utilizing a short lived variable:

a = 5
b = 10

temp = a
a = b
b = temp

print("a =", a)
print("b =", b)

Right here’s a breakdown of the code:

  1. temp = a: The worth of a is assigned to the momentary variable temp.
  2. a = b: The worth of b is assigned to a. Now each variables a and b have the identical worth (10).
  3. b = temp: The unique worth of a that was saved within the momentary variable temp is now assigned again to b.

After executing this code, the values of a and b will likely be swapped, with a holding the worth 10 and b holding the worth 5.

Utilizing a short lived variable is an easy and intuitive strategy to swap the values of two variables in Python. Nevertheless, Python additionally gives different strategies for swapping values with out introducing a short lived variable, similar to tuple unpacking (a, b = b, a).

Swapping With Array or Listing

You may also use an array to swap components in a Python listing. To do that, you might want to pop the weather at each positions pos1 and pos2, storing them in momentary variables. Then, insert these components again into the listing at their reverse positions.

def swap_positions_with_array(listing, pos1, pos2):
    first_element = listing.pop(pos1)
    second_element = listing.pop(pos2 - 1)
    listing.insert(pos1, second_element)
    listing.insert(pos2, first_element)
    return listing

The swap_positions_with_array operate is designed to swap two components at particular positions inside an inventory, with out utilizing the everyday tuple unpacking methodology. It does this by instantly manipulating the listing utilizing pop and insert strategies. Right here’s the way it works:

  1. first_element = listing.pop(pos1): Removes the ingredient at pos1 from the listing and shops it in first_element.
  2. second_element = listing.pop(pos2 - 1): After the primary pop, all components shift one place to the left. So, the ingredient at pos2 is now at pos2 - 1. This ingredient is eliminated and saved in second_element.
  3. listing.insert(pos1, second_element): Inserts second_element at pos1. This shifts components to the proper from this place onwards.
  4. listing.insert(pos2, first_element): Inserts first_element on the authentic pos2. Since we had eliminated one ingredient earlier than this level, the insert will place first_element accurately at pos2.

The operate then returns the modified listing with the weather swapped.


Let’s say we’ve got an inventory [10, 20, 30, 40, 50] and we wish to swap the weather at positions 1 (the ingredient 20) and 3 (the ingredient 40).

my_list = [10, 20, 30, 40, 50]
swapped_list = swap_positions_with_array(my_list, 1, 3)
print(swapped_list)  # Output will likely be [10, 40, 30, 20, 50]

Within the output, the weather 20 and 40 have been swapped.

Reminiscence and Arithmetic Operations in Swap Perform

One other strategy is utilizing arithmetic operations to swap values with out a momentary variable, primarily when working with numeric variables. This methodology entails varied mathematical operations like addition, subtraction, or bitwise operators.

Right here’s an instance utilizing addition and subtraction:

x = 5
y = 10
x = x + y
y = x - y
x = x - y

This code snippet is a technique of swapping the values of two variables with out utilizing a short lived third variable. Right here’s a step-by-step clarification of the way it works:


  1. x = x + y provides the worth of y to x:
    • Now x is 15 (the sum of the preliminary values of x and y).
    • y stays 10.
  2. y = x - y subtracts the brand new worth of x by the present worth of y to seek out the unique worth of x:
    • Now y is 5 (which was the preliminary worth of x).
    • x stays 15.
  3. x = x - y subtracts the brand new worth of y from the present worth of x to seek out the unique worth of y:
    • Now x is 10 (which was the preliminary worth of y).
    • y stays 5.

After these operations, x and y have successfully swapped values:

It is a basic programming trick used to save lots of reminiscence by avoiding the necessity for an extra variable to carry a worth briefly in the course of the swap.

Sorting and Swap Perform

When working with lists in Python, chances are you’ll have to kind or rearrange information. The kind operate is a useful device for ordering components in an inventory. Along with the built-in sorting strategies, you may as well implement customized sorting strategies by using the idea of the swap operate.

A swap operate is a straightforward methodology that exchanges the positions of two components in an inventory. It may be significantly helpful in customized sorting algorithms, similar to bubble kind or insertion kind. Right here’s how one can create a primary swap operate in Python:

def swap(arr, i, j):
    arr[i], arr[j] = arr[j], arr[i]

On this operate, arr is the enter listing, and i and j are the indices of the weather you wish to swap. The operate instantly manipulates the unique listing and doesn’t return a brand new listing.

Now, let’s see how you need to use the swap operate in a easy sorting algorithm like bubble kind:

def bubble_sort(arr):
    n = len(arr)
    for i in vary(n):
        for j in vary(0, n-i-1):
            if arr[j] > arr[j+1]:
                swap(arr, j, j+1)

On this implementation, the bubble_sort operate iterates via the listing and compares adjoining components. If the present ingredient is better than the subsequent, it calls the swap operate to swap their positions. This course of continues till the listing is sorted.

Steadily Requested Questions

How are you going to swap two components in a Python array?

To swap two components in a Python array (often known as an inventory), you need to use a short lived variable to retailer the worth of 1 ingredient whereas assigning the worth of the opposite ingredient. For instance:

list_name = [1, 2, 3, 4]
index1 = 1
index2 = 3
temp = list_name[index1]
list_name[index1] = list_name[index2]
list_name[index2] = temp

It will swap the weather at index positions 1 and three within the listing list_name.

What’s the course of for swapping values of two variables in Python?

In Python, you’ll be able to swap values of two variables with out utilizing a short lived variable. The strategy generally used is named tuple unpacking. Right here’s an instance:

x = 5
y = 10
x, y = y, x

Now, x may have the worth 10, and y may have the worth 5.

How are you going to reverse an array or string in Python?

To reverse an array (listing) or string in Python, you need to use slicing. For instance:

my_list = [1, 2, 3, 4]
my_string = "Good day"
reversed_list = my_list[::-1]
reversed_string = my_string[::-1]

After executing this code, reversed_list will comprise [4, 3, 2, 1] and reversed_string will comprise "olleH".

What’s the position of a short lived variable in variable swapping?

A short lived variable is used to briefly retailer the worth of a variable when you might want to swap the values of two variables. This methodology creates a short lived “place holder” to forestall information loss in the course of the swapping course of. In Python, nonetheless, utilizing a short lived variable is pointless due to tuple unpacking, as talked about earlier.

How is the exchange operate utilized in Python?

The exchange() operate in Python is a string methodology that means that you can exchange occurrences of a given substring with a brand new substring. Right here’s an instance of how one can use the exchange() operate:

original_string = "I really like apples and apples are tasty."
new_string ="apples", "oranges")

On this instance, new_string will comprise the textual content: "I really like oranges and oranges are tasty."

Can bubble kind or different sorting strategies be used to swap components?

Sure, bubble kind and different sorting algorithms can be utilized to swap components in an inventory in the course of the sorting course of. In truth, swapping components is an important a part of many sorting algorithms. For instance, throughout bubble kind, adjoining components are in contrast and swapped if they’re within the fallacious order, finally sorting the listing via a sequence of swaps. Equally, different sorting algorithms like choice kind and insertion kind additionally contain ingredient swapping as a main operation.

🧑‍💻 Advisable: 55 Greatest Concepts to Make Cash with Python

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