Python – Extract digits from Tuple list

Last Updated : 21 Apr, 2023

Sometimes, while working with Python lists, we can have a problem in which we need to perform extraction of all the digits from tuple list. This kind of problem can find its application in data domains and day-day programming. Let’s discuss certain ways in which this task can be performed.

Input : test_list = [(15, 3), (3, 9)]
Output : [9, 5, 3, 1]

Input : test_list = [(15, 3)]
Output : [5, 3, 1]

Method #1: Using map() + chain.from_iterable() + set() + loop
The combination of above functions can be used to solve this problem. In this, we perform the task of flattening list using chain.from_iterable(), and then the digits are extracted using brute method. set() is used to remove duplicate digits.

Python3

# Python3 code to demonstrate working of 
# Extract digits from Tuple list
# Using map() + chain.from_iterable() + set() + loop
from itertools import chain
 
# initializing list
test_list = [(15, 3), (3, 9), (1, 10), (99, 2)]
 
# printing original list
print("The original list is : " + str(test_list))
 
# Extract digits from Tuple list
# Using map() + chain.from_iterable() + set() + loop
temp = map(lambda ele: str(ele), chain.from_iterable(test_list))
res = set()
for sub in temp:
    for ele in sub:
        res.add(ele)
 
# printing result 
print("The extracted digits : " + str(res)) 

Output

The original list is : [(15, 3), (3, 9), (1, 10), (99, 2)]
The extracted digits : {'1', '0', '3', '2', '9', '5'}

Time Complexity: O(n*m), where n is the length of the input list and m is the maximum length of any tuple element in the list.
Auxiliary Space: O(k), where k is the number of unique digits in the input list. This is because the set data structure is used to store the extracted digits.

Method #2: Using regex expression
This is yet another way in which this task can be performed. In this, an appropriate regex expression is used to extract the required unique digits.

Python3

# Python3 code to demonstrate working of 
# Extract digits from Tuple list
# Using regex expression
import re
 
# initializing list
test_list = [(15, 3), (3, 9), (1, 10), (99, 2)]
 
# printing original list
print("The original list is : " + str(test_list))
 
# Extract digits from Tuple list
# Using regex expression
temp = re.sub(r'[\[\]\(\), ]', '', str(test_list))
res = [int(ele) for ele in set(temp)]
 
# printing result 
print("The extracted digits : " + str(res)) 

Output

The original list is : [(15, 3), (3, 9), (1, 10), (99, 2)]
The extracted digits : [5, 9, 2, 0, 1, 3]

Time complexity: O(n), where n is the length of the input list.
Auxiliary space: O(n), where n is the length of the input list.

Method #3: Using list(),str(),map(),set() methods .

Initially converted all elements of tuple to string and concatenated them.Later used set() method to remove the duplicates, converted string elements to integer elements and finally converted them to list datatype.

Python3

# Python3 code to demonstrate working of
# Extract digits from Tuple list
 
# initializing list
test_list = [(15, 3), (3, 9), (1, 10), (99, 2)]
 
# printing original list
print("The original list is : " + str(test_list))
x=""
# Extract digits from Tuple list
for i in test_list:
    for j in i:
        x+=str(j)
res=list(map(int,set(x)))
# printing result
print("The extracted digits : " + str(res))

Output

The original list is : [(15, 3), (3, 9), (1, 10), (99, 2)]
The extracted digits : [2, 3, 0, 1, 9, 5]

Method#4: Using list Comprehension

Python3

# Initializing list
test_list = [(15, 3), (3, 9), (1, 10), (99, 2)]
 
# Printing original list
print("The original list is : " + str(test_list))
 
# Extracting digits from Tuple list using list comprehensions
temp = ''.join([str(i) for sublist in test_list for i in sublist])
result = set(temp)
result = [int(i) for i in result]
# Printing result
print("The extracted digits : " + str(list(result)))
#This code is contributed by Vinay Pinjala.

Output

The original list is : [(15, 3), (3, 9), (1, 10), (99, 2)]
The extracted digits : ['0', '9', '1', '3', '5', '2']

Time complexity : O(n)
Auxiliary Space : O(n)

METHOD 5:Using reduce and set

APPROACH:

This program extracts digits from a tuple list using the reduce function from the functools module.

ALGORITHM:

1.Define the tuple list.
2.Use the reduce function to concatenate all the elements of the tuple into a single string.
3.Convert each string into a set to remove duplicates.
4.Merge all sets into a single set.
5.Convert the set of strings into a set of individual digits.
6.Print the original list and the extracted digits.

Python3

from functools import reduce
 
tup_list = [(15, 3), (3, 9), (1, 10), (99, 2)]
 
digit_list = set(reduce(lambda a,b: str(a) + str(b), tup) for tup in tup_list)
digit_list = set(digit for string in digit_list for digit in string)
 
print("The original list is:", tup_list)
print("The extracted digits:", digit_list)

Output

The original list is: [(15, 3), (3, 9), (1, 10), (99, 2)]
The extracted digits: {'9', '3', '1', '5', '2', '0'}

Time Complexity: O(nlogn) (where n is the number of tuples in the list)
Space Complexity: O(n) (where n is the number of digits extracted)

METHOD 6: Using heapq:

Algorithm:

Initialize a list ‘test_list’ with tuples of integers.
Print the original list ‘test_list’.
Using a list comprehension, extract all the digits from the tuples and join them as a single string.
Convert the string to a set to extract only unique digits.
Convert the set back to a list and sort the list.
Print the resulting list of unique digits.

Python3

import heapq
 
# Initializing list
test_list = [(15, 3), (3, 9), (1, 10), (99, 2)]
 
# Printing original list
print("The original list is : " + str(test_list))
 
# Extracting digits from Tuple list using heapq
result = []
for tpl in test_list:
    result.extend(list(tpl))
 
# Converting the result list to heap
heapq.heapify(result)
 
# Extracting unique digits from heap
unique_digits = set()
while result:
    digits = str(heapq.heappop(result))
    for digit in digits:
        unique_digits.add(int(digit))
 
# Printing result
print("The extracted digits : " + str(list(unique_digits)))
#This code is contributed by Rayudu.

Output

The original list is : [(15, 3), (3, 9), (1, 10), (99, 2)]
The extracted digits : [0, 1, 2, 3, 5, 9]

Time Complexity:

Initializing the list takes O(1) time.
Printing the list takes O(n) time, where n is the number of tuples in the list.
Using a list comprehension to extract digits takes O(nk) time, where k is the average number of digits in each tuple.
Converting the string to a set takes O(k) time, where k is the total number of digits.
Converting the set back to a list and sorting takes O(k log k) time.
Printing the resulting list takes O(k) time.
Therefore, the overall time complexity of the code is O(nk + k log k).

Space Complexity:

Initializing the list takes O(n) space, where n is the number of tuples in the list.
Extracting digits using list comprehension creates a new list which takes O(nk) space.
Converting the string to a set takes O(k) space.
Converting the set back to a list takes O(k) space.
Therefore, the overall space complexity of the code is O(nk + 2k) or simply O(nk).