Find Tuple Indices from Other Tuple List in Python

To find the tuple indices from other tuple list we can use enumerate function and index function of Python.

An ordered and immutable group of objects is referred to as a tuple. Sequences are just what tuples and lists both are. Tuples and lists vary in that tuples cannot be altered, although lists may, and because tuples use parentheses while lists use square brackets.

Example

Assume we have taken an input list containing tules and another search tuple list. We will now search the indices of the search tuple list in the given input list

Input

inputList = [(1, 3), (2, 4), (5, 7), (6, 8)]
searchTupleList = [(1, 3), (5, 7), (3, 8), (7, 2)]

Output

Index of searched tuple in the input list: [0, 2]

Using list comprehension, lookup dictionary and enumerate() function

The enumerate() method adds a counter to an iterable and returns the enumerate object.

Syntax

enumerate(iterable, start=0)

Parameters

• iterable - It can be any sequence/object/iterable supporting iteration

• start - enumerate() begins counting from this value. If the start is not specified, the value 0 is used.

Algorithm (Steps)

Following are the Algorithm/steps to be followed to perform the desired task -.

• Create a variable to store the input list of tuples.

• Print the input list.

• Create another variable to store the input search tuple list whose values are to be searched in the input list.

• Use the enumerate() function to get the element and index values of the input list as value-key pairs.

• Use the list comprehension to traverse through the searchTuple list and check whether the element exists in the above lookup dictionary.

• If it exists then store its index of it.

Example

The following program returns tuple indices from other tuple list using list comprehension, lookup dictionary, and enumerate() function -

# input list of tuples
inputList = [(1, 3), (2, 4), (5, 7), (6, 8)]
# printing input list
print("Input List: ", inputList)
# input search tuple list whose values are to be searched in input list
searchTupleList = [(10, 6), (5, 7), (3, 8), (7, 2)]
# getting the element and index values of input list as a value-key pairs
searchDict = {v: k for k, v in enumerate(inputList)}
# Checking whether the tuple exits and if exists then storing the index of it.
resultantList = [searchDict[idx]
   for idx in searchTupleList if idx in searchDict]
#  printing resultant list of index
print("Index of searched tuple in input list:", resultantList)

Output

On executing, the above program will generate the following output -

Input List:  [(1, 3), (2, 4), (5, 7), (6, 8)]
Index of searched tuple in input list: [2]

Using list comprehension and enumerate() function

When you wish to build a new list based on the values of an existing list, list comprehension provides a shorter/concise syntax.

Example

The following program returns tuple indices from other tuple list using list comprehension and enumerate() function -

# input list of tuples
inputList = [(1, 3), (2, 4), (5, 7), (6, 8)]	
# printing input list
print("Input List: ", inputList)
# input search tuple list whose values are to be searched in input list
searchTupleList = [(1, 3), (5, 7), (3, 8), (7, 2)]
# Getting the result using the concise syntax using list comprehension
resultantList = [i for i, value in enumerate(inputList) for element in searchTupleList if element == value]
# printing resultant list of indices
print("Index of searched tuple in input list:", resultantList)

Output

On executing, the above program will generate the following output -

Input List:  [(1, 3), (2, 4), (5, 7), (6, 8)]
Index of searched tuple in input list: [0, 2]

Using the index() method

The position at the first occurrence of the provided value is returned by the index() method.

Syntax

list.index(element)

Algorithm (Steps)

Following are the Algorithm/steps to be followed to perform the desired task -.

• Create a variable to store the input list of tuples.

• Print the input list.

• Create another variable to store the input search tuple list whose values are to be searched in the input list.

• Initialize a new empty list to store the resultant list.

• Use the for loop to traverse through the searchTupleList.

• Use the if conditional statement to check whether the current element is present in the input list.

• Use the index() function to get the index of the current element and append it to the resultant list using the append() function( adds the element to the list at the end).

• Print the resultant list.

Example

The following program returns tuple indices from other tuple list using list comprehension and enumerate() function -

# input list of tuples
inputList = [(1, 3), (2, 4), (5, 7), (6, 8)]		
# printing input list
print("Input List: ", inputList)
# input search tuple list whose values are to be searched in the input list
searchTupleList = [(10, 6), (5, 7), (3, 8), (7, 2)]
# Creating a variable to store the result indices list 
resultantList=[]
# traversing through searchTupleList
for p in searchTupleList:
    # checking whether the current element is present in an input list 
	if p in inputList:
       #  getting the index of current element and appending it to the resultant list 
		resultantList.append(inputList.index(p))
# printing resultant list of indices
print("Index of searched tuple in input list:", resultantList)

Output

On executing, the above program will generate the following output -

Input List:  [(1, 3), (2, 4), (5, 7), (6, 8)]
Index of searched tuple in input list: [2]

Conclusion

In this article, we have learned how to find tuple indices from other tuple lists using 3 different methods. We also learned how to iterate through the iterable's index and element values using the enumerate() function. Finally, we learned how to use the index() function to retrieve the tuple pairs.