Python Program to Compare Two Dictionary Elements

A dictionary is a powerful data type in Python that allows you to store data as key-value pairs. In this article, we will discuss how to compare two dictionary elements in Python. We will introduce the syntax for comparing dictionary elements and provide examples of how to perform comparisons.

Dictionaries in Python

In Python, a dictionary is created by placing a list of elements within curly braces {}, separated by commas (IV). A dictionary can store pairs of values: a key and its corresponding element.

Dictionary values can be of any data type and can be repeated, while keys cannot be repeated and must be immutable and unique. Dictionary key names are case-sensitive. Dictionaries can also be created using the built-in function dict(). An empty dictionary can be created by enclosing curly braces { }.

We can declare a dictionary as follows:

thisdict = { "brand": "Ford", "model": "Mustang", year": 1964 }

In this article, we’ll look at how to compare two dictionary elements in Python using three different methods.

Using the equality operator ( == ) )

In this method, we will use the double equality comparison operator to compare two strings. The == operator returns true when the left-hand operator and the right-hand operator are equal, and returns false when they are not equal.

If the two dictionaries given to us are equal and identical to each other, this operator will return true, and we can conclude that the two dictionaries are equal. On the other hand, it returns false if they are not equal.

Example

In the following example, we use the == operator to compare two dictionaries.

dict1 = { 'first' : 'apple' , 'second' : 'orange' , 'third' : 'mango' }
dict2 = { 'first' : 'apple' , 'second' : 'orange' , 'third' : 'grapes'}
if dict1 == dict2:
print (" dict1 is equal to dict2 ")
else:
print (" dict1 is not equal to dict2 ")

Output

The output of the above code will be –

dict1 is not equal to dict2

Using a Loop to Compare Two Dictionaries

In this method, we will compare the elements of the two dictionaries one by one by iterating over the length of one dictionary and comparing the key and value of each iteration with the corresponding key and value pair in the other dictionary.

We will also check the lengths of the two dictionaries; if they are different, we can conclude that the two dictionaries are not equal. To get the value corresponding to a key in a dictionary, we use the get function, which gives the value of the key as an argument.

Example

In the following example, we will.

dict1 = { 'first' : 'apple' , 'second' : 'orange' , 'third' : 'mango' }
dict2 = { 'first' : 'banana' , 'second' : 'guava' , 'third' : 'grapes'}
if len (dict1) != len (dict2):
    print ("The dictionaries are not equal ")
else:
    flag=0
    for i in dict1:
        if dict1.get(i) != dict2.get(i):
flag=1
break
if flag==0:
print (" dict1 is equal to dict2 ")
else:
print (" dict1 is not equal to dict2 ")

Output

The output of the above program will be as follows: -.

dict1 is not equal to dict2

Using List Comprehension

In this method, we will use list comprehension to compare two dictionaries. List comprehension is a shorter way to write a for loop over a list, tuple, or dictionary. In this method, we will iterate over one of the dictionaries and compare whether the values for the same key in both dictionaries are the same. If they are the same, the dictionaries will be equal; if they are not, they will be unequal.

Example

The following Python code shows how we can use list comprehension to compare two given dictionaries and print the results.

dict1 = { 'first' : 'apple' , 'second' : 'orange' , 'third' : 'mango' }
dict2 = { 'first' : 'banana' , 'second' : 'guava', 'third': 'grapes'}
ans = all ( dict2.get (key) == value for key , value in dict1.items() )
if ans == 'true':
print ("dict1 and dict2 are equal")
else:
print ("dict1 and dict2 are not equal")

Output

The output of the above code will be as follows —

dict1 and dict2 are not equal equal

Summary

In this article, we learned about dictionaries in Python and where we can use them. We also learned how to compare two given dictionaries. We encountered three different methods to compare two dictionaries.

The first method was to use the equality operator (==). The second method was to use iteration to check each key-value pair of both dictionaries. In the last method, we used Python’s list comprehension method to iterate over the key-value pairs of a dictionary, check the keys in both dictionaries, and compare them.

The time complexity of the first method is O(1) because it uses simple comparison. The time complexity of the other two methods is O(n), where n is the length of the dictionary.