How can I sort one list by values from another list in Python?

We can sort a list by values from another list by setting up the 2^nd list as index numbers for the values in the 1^st List in sorted order.

Sort a List by values from another list

Example

In this example, we will sort a list by values from another list i.e. the 2^nd list will have the index in the order in which they are placed in sorted order −

# Two Lists
list1 = ['BMW', 'Toyota', 'Audi', 'Tesla', 'Hyundai']
list2 = [2, 5, 1, 4, 3]

print("List1 = \n",list1)
print("List2 (indexes) = \n",list2)

# Sorting the List1 based on List2
res = [val for (_, val) in sorted(zip(list2, list1), key=lambda x: x[0])]
print("\nSorted List = ",res)

Output

List1 = 
 ['BMW', 'Toyota', 'Audi', 'Tesla', 'Hyundai']
List2 (indexes) = 
 [2, 5, 1, 4, 3]

Sorted List =  ['Audi', 'BMW', 'Hyundai', 'Tesla', 'Toyota']

Sort a list by values from another list using Dictionary

Example

In this example, we will sort a list by values another list. We will add both the lists in a Dictionary and then usethe key value in Dictionary with lambda to sort.

# Two Lists
list1 = ['BMW', 'Toyota', 'Audi', 'Tesla', 'Hyundai']
list2 = [2, 5, 1, 4, 3]

print("List1 = \n",list1)
print("List2 (indexes) = \n",list2)

# Blank dictionary
newDict = {}

# Blank list
outList = []

# Both the lists in our dictionary newDict
newDict = {list1[i]: list2[i] for i in range(len(list2))}

# Sorting using the sorting() based on key and values
# Using lambda as well
s = {k: v for k, v in sorted(newDict.items(), key=lambda item: item[1])}

# Element addition in the list
for i in s.keys():
   outList.append(i)

print("\nSorted List = \n",outList)

Output

List1 = 
 ['BMW', 'Toyota', 'Audi', 'Tesla', 'Hyundai']
List2 (indexes) = 
 [2, 5, 1, 4, 3]

Sorted List = 
['Audi', 'BMW', 'Hyundai', 'Tesla', 'Toyota']

AmitDiwan

Updated on: 16-Sep-2022

3K+ Views

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