In this article, we are going to see how to iterate through a nested List. A list can be used to store multiple Data types such as Integers, Strings, Objects, and also another List within itself. This sub-list which is within the list is what is commonly known as the Nested List.
Iterating through a Nested List
Lets us see how a typical nested list looks like :
There are multiple ways to iterate through a Nested List:
Method 1: Use of the index to iterate through the list
Use of Positive Index:
# code list = [ 10 , 20 , 30 , 40 , [ 80 , 60 , 70 ]]
# Printing sublist at index 4 print ( list [ 4 ])
# Printing 1st element of the sublist print ( list [ 4 ][ 0 ])
# Printing 2nd element of the sublist print ( list [ 4 ][ 1 ])
# Printing 3rd element of the sublist print ( list [ 4 ][ 2 ])
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Output:
[80, 60, 70] 80 60 70
Use of Negative Index
# code list = [ 10 , 20 , 30 , 40 , [ 80 , 60 , 70 ]]
# Printing sublist at index 4 print ( list [ - 1 ])
# Printing 1st element of the sublist print ( list [ - 1 ][ - 3 ])
# Printing 2nd element of the sublist print ( list [ - 1 ][ - 2 ])
# Printing 3rd element of the sublist print ( list [ - 1 ][ - 1 ])
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Output:
[80, 60, 70] 80 60 70
Method 2: Use of loop to iterate through the list
# code # LIST list = [[ "Rohan" , 60 ], [ "Aviral" , 21 ],
[ "Harsh" , 30 ], [ "Rahul" , 40 ],
[ "Raj" , 20 ]]
# looping through nested list using indexes for names in list :
print (names[ 0 ], "is" , names[ 1 ],
"years old." )
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Output:
Rohan is 60 years old. Aviral is 21 years old. Harsh is 30 years old. Rahul is 40 years old. Raj is 20 years old.
Use of Temporary Variables inside a loop.
# code # LIST list = [[ "Rohan" , 60 ], [ "Aviral" , 21 ],
[ "Harsh" , 30 ], [ "Rahul" , 40 ],
[ "Raj" , 20 ]]
# looping through nested list using multiple # temporary variables for name, age in list :
print (name, "is" ,
age, "years old." )
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Output:
Rohan is 60 years old. Aviral is 21 years old. Harsh is 30 years old. Rahul is 40 years old. Raj is 20 years old.
Method 3: Use of Slicing
# code # list list = [ 10 , 20 , 30 , 40 ,
[ 80 , 60 , 70 ]]
# print the entire Sublist at index 4 print ( list [ 4 ][:])
# printing first two element print ( list [ 4 ][ 0 : 2 ])
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Output:
[80, 60, 70] [80, 60]