Python | Remove tuples from list of tuples if greater than n
Last Updated :
09 Apr, 2023
Given a list of a tuple, the task is to remove all the tuples from list, if it’s greater than n (say 100). Let’s discuss a few methods for the same.
Method #1: Using lambda
STEPS:
- Initialize a list of tuples: ini_tuple = [(‘b’, 100), (‘c’, 200), (‘c’, 45), (‘d’, 876), (‘e’, 75)]
- Print the initial list: print(“intial_list”, str(ini_tuple))
- Define the condition that determines which tuples should be removed from the list. In this case, we want to remove tuples where the second element (index 1) is greater than 100.
- Use a list comprehension to iterate over each tuple in ini_tuple and create a new list containing only those tuples that satisfy the condition: result = [i for i in ini_tuple if i[1] <= 100]
- Print the resultant tuple list: print(“Resultant tuple list: “, str(result))
Python3
ini_tuple = [('b', 100), ('c', 200), ('c', 45),
('d', 876), ('e', 75)]
print("intial_list", str(ini_tuple))
result = [i for i in ini_tuple if i[1] <= 100]
print("Resultant tuple list: ", str(result))
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Output
intial_list [('b', 100), ('c', 200), ('c', 45), ('d', 876), ('e', 75)]
Resultant tuple list: [('b', 100), ('c', 45), ('e', 75)]
Time complexity: O(n), where n is the number of tuples in the initial list.
Auxiliary space: O(m), where m is the number of tuples that satisfy the condition.
Method #2: Using filter + lambda
Python3
ini_tuple = [('b', 100), ('c', 200), ('c', 45),
('d', 876), ('e', 75)]
print("intial_list", str(ini_tuple))
result = list(filter(lambda x: x[1] <= 100, ini_tuple))
print("Resultant tuple list: ", str(result))
|
Output
intial_list [('b', 100), ('c', 200), ('c', 45), ('d', 876), ('e', 75)]
Resultant tuple list: [('b', 100), ('c', 45), ('e', 75)]
Time complexity: O(n), where n is the number of tuples in tuple.
Auxiliary space: O(m), where m is the number of tuples in result.
Method #3: Using Naive Method
Python3
ini_tuple = [('b', 100), ('c', 200), ('c', 45),
('d', 876), ('e', 75)]
print("intial_list", str(ini_tuple))
result = []
for i in ini_tuple:
if i[1] <= 100:
result.append(i)
print("Resultant tuple list: ", str(result))
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Output
intial_list [('b', 100), ('c', 200), ('c', 45), ('d', 876), ('e', 75)]
Resultant tuple list: [('b', 100), ('c', 45), ('e', 75)]
Time complexity: O(n), where n is the number of tuples in the ini_tuple list.
Auxiliary space: O(m), where m is the number of tuples in the result list
Method #4: Using list comprehension
Python3
tup = [('b', 100), ('c', 200), ('c', 45),('d', 876), ('e', 75)]
print([i for i in tup if i[1] <= 100])
|
Output
[('b', 100), ('c', 45), ('e', 75)]
Time Complexity: O(n)
Auxiliary Space: O(1)
Method: Using enumerate function
Python3
tup = [('b', 100), ('c', 200), ('c', 45),('d', 876), ('e', 75)]
print([i for a,i in enumerate(tup) if i[1] <= 100])
|
Output
[('b', 100), ('c', 45), ('e', 75)]
Time complexity: O(n), where n is the length of the input list tup.
Auxiliary space: O(n), because the list comprehension creates a new list to store the filtered tuples.
Alternative method:
Python3
tup = [('b', 100), ('c', 200), ('c', 45),('d', 876), ('e', 75)]
x=[i[1] for i in tup]
x=list(filter(lambda i:(i<=100),x))
print(x)
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Time complexity: O(n), where n is the length of the input list ‘tup’,
Auxiliary space: O(m), where m is the number of elements in the resulting list ‘x’.
Alternative method:
One additional approach to remove tuples from a list of tuples if their second element is greater than a certain value n is to use the remove method of the list object. This method removes the first occurrence of the specified value in the list.
For example:
Python3
tup = [('b', 100), ('c', 200), ('c', 45),('d', 876), ('e', 75)]
for t in tup:
if t[1] > 100:
tup.remove(t)
print(tup)
|
Output
[('b', 100), ('c', 45), ('e', 75)]
Time complexity: O(n^2) as the remove method takes O(n) time to remove an element from the list and the loop iterates through the list n times.
Auxiliary Space: O(1) as it does not create any additional data structures.
Method: Using a recursive function
Python3
def remove_tuple(start,oldlist,n,newlist):
if start==len(oldlist):
return newlist
if oldlist[start][1]>n:
pass
else:
newlist.append(oldlist[start])
return remove_tuple(start+1,oldlist,n,newlist)
tup = [('b', 100), ('c', 200), ('c', 45),('d', 876), ('e', 75)]
n=100
res=remove_tuple(0,tup,n,[])
print(res)
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Output
[('b', 100), ('c', 45), ('e', 75)]
Time complexity: O(n)
Auxiliary Space: O(n).
Method: Using itertools.filterfalse function:
Algorithm:
Define the initial tuple.
Define the condition to remove tuples (second element <= 100).
Use itertools.filterfalse to get the tuples that meet the condition.
Use filter to remove the tuples in the filtered list from the initial tuple.
Print the result.
Python3
import itertools
ini_tuple = [('b', 100), ('c', 200), ('c', 45),
('d', 876), ('e', 75)]
print("intial_list", str(ini_tuple))
result = list(filter(lambda x: x not in list(itertools.filterfalse(lambda y: y[1] <= 100, ini_tuple)), ini_tuple))
print("Resultant tuple list: ", str(result))
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Output
intial_list [('b', 100), ('c', 200), ('c', 45), ('d', 876), ('e', 75)]
Resultant tuple list: [('b', 100), ('c', 45), ('e', 75)]
Time Complexity:
The itertools.filterfalse function in step 3 has a time complexity of O(N) where N is the number of tuples in the initial list.
The filter function in step 4 has a time complexity of O(N) where N is the number of tuples in the initial list.
Therefore, the overall time complexity of the code is O(N).
Auxiliary Space:
The space complexity of the code is O(N) where N is the number of tuples in the initial list. This is because we are creating a new list for the filtered tuples and another list for the result.
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