Python – Mapping Matrix with Dictionary

Given a Matrix, map its values with dictionary values.

Input : test_list = [[4, 2, 1], [1, 2, 3]], sub_dict = {1 : “gfg”, 2: “best”, 3 : “CS”, 4 : “Geeks”}
Output : [[‘Geeks’, ‘best’, ‘gfg’], [‘gfg’, ‘best’, ‘CS’]]
Explanation : Matrix elements are substituted using dictionary.

Input : test_list = [[4, 2, 1]], sub_dict = {1 : “gfg”, 2: “best”, 4 : “Geeks”}
Output : [[‘Geeks’, ‘best’, ‘gfg’]]
Explanation : Matrix elements are substituted using dictionary.

Method #1 : Using loop

This is brute way in which this task can be performed. In this, we iterate for all the elements of Matrix and map from dictionary.

Python3

# Python3 code to demonstrate working of
# Mapping Matrix with Dictionary
# Using loop

# initializing list
test_list = [[4, 2, 1], [1, 2, 3], [4, 3, 1]]

# printing original list
print("The original list : " + str(test_list))

# initializing dictionary
sub_dict = {1 : "gfg", 2: "best", 3 : "CS", 4 : "Geeks"}

# Using loop to perform required mapping
res = []
for sub in test_list:
    temp = []
    for ele in sub:

        # mapping values from dictionary
        temp.append(sub_dict[ele])
    res.append(temp)

# printing result
print("Converted Mapped Matrix : " + str(res))

Output

The original list : [[4, 2, 1], [1, 2, 3], [4, 3, 1]]
Converted Mapped Matrix : [['Geeks', 'best', 'gfg'], ['gfg', 'best', 'CS'], ['Geeks', 'CS', 'gfg']]

Method #2 : Using list comprehension

This is yet another way in which this task can be performed. This is just shorthand to above method. 

Python3

# Python3 code to demonstrate working of
# Mapping Matrix with Dictionary
# Using list comprehension

# initializing list
test_list = [[4, 2, 1], [1, 2, 3], [4, 3, 1]]

# printing original list
print("The original list : " + str(test_list))

# initializing dictionary
sub_dict = {1 : "gfg", 2: "best", 3 : "CS", 4 : "Geeks"}

# Using list comprehension to perform required mapping
# in one line
res = [[sub_dict[val] for val in sub] for sub in test_list]

# printing result
print("Converted Mapped Matrix : " + str(res))

Output

The original list : [[4, 2, 1], [1, 2, 3], [4, 3, 1]]
Converted Mapped Matrix : [['Geeks', 'best', 'gfg'], ['gfg', 'best', 'CS'], ['Geeks', 'CS', 'gfg']]