How to Check if All Values in a Python Dictionary are Equal

This guide demonstrates various methods for checking if all values in a Python dictionary are equal. We'll explore using the all() function with a generator expression (the most concise and Pythonic way), using set operations, using list.count() and using a for loop, explaining the trade-offs of each.

Using all() with a Generator Expression (Recommended)

The most Pythonic and efficient way to check if all dictionary values are equal is to use the all() function combined with a generator expression:

my_dict = {
    'tutorial': 5,
    'reference': 5,
    'com': 5
}

first_value = list(my_dict.values())[0] # Get first value.
all_equal = all(value == first_value for value in my_dict.values())
print(all_equal)    # Output: True

my_dict = {
    'tutorial': 5,
    'reference': 6, # Not the same value
    'com': 5
}
first_value = list(my_dict.values())[0]
all_equal = all(value == first_value for value in my_dict.values())
print(all_equal)    # Output: False

• first_value = list(my_dict.values())[0]: This line gets the first value in the dictionary. We'll compare all other values to this one. We convert the dict_values view object to a list to allow indexing.
• all(value == first_value for value in my_dict.values()): This is the core logic.
  • my_dict.values(): Gets a "view" of all the values in the dictionary. This is efficient; it doesn't create a new list.
  • value == first_value for value in my_dict.values(): This is a generator expression. It efficiently iterates through the dictionary's values and, for each value, checks if it's equal to first_value. It yields a sequence of True or False values.
  • all(...): The all() function returns True if all values produced by the generator expression are True. It short-circuits: as soon as it finds a False value, it stops and returns False. This makes it efficient.

This method is concise, readable, and efficient because it avoids creating intermediate lists or sets unless necessary.

Using Set Operations (Efficient for Unique Values)

If you only care about whether all values are equal (and don't need to know what that value is), you can convert the dictionary's values to a set. If all values are equal, the set will have a length of 1:

my_dict = {
    'tutorial': 5,
    'reference': 5,
    'com': 5
}

all_equal = len(set(my_dict.values())) == 1
print(all_equal)  # Output: True

my_dict = {
    'tutorial': 5,
    'reference': 6,
    'com': 5
}
all_equal = len(set(my_dict.values())) == 1
print(all_equal)  # Output: False

• set(my_dict.values()): Creates a set from the dictionary's values. Sets automatically remove duplicates.
• len(...) == 1: Checks if the resulting set has only one element. If it does, all original values were identical.

note

This method is very efficient, especially if the dictionary has many values, but it doesn't tell you what the common value is. It only tells you if they are all equal.

Using list.count()

You can use list.count(), but this is generally less efficient than the all() or set-based approaches:

my_dict = {
    'tutorial': 5,
    'reference': 5,
    'com': 5
}

first_value = list(my_dict.values())[0]
all_equal = list(my_dict.values()).count(first_value) == len(my_dict)
print(all_equal)  # Output: True

my_dict = {
    'tutorial': 5,
    'reference': 6,
    'com': 5
}

first_value = list(my_dict.values())[0]
all_equal = list(my_dict.values()).count(first_value) == len(my_dict)
print(all_equal)  # Output: False

• This method requires creating a list of all values and then counting the occurrences of the first value. It is inefficient for larger dictionaries.

Using a for Loop (Most Explicit)

For completeness, here's how you'd do it with a for loop:

my_dict = {
    'tutorial': 5,
    'reference': 5,
    'com': 5
}

all_values_equal = True
first_value = list(my_dict.values())[0]

for value in my_dict.values():
    if value != first_value:
        all_values_equal = False
        break  # Exit loop as soon as a difference is found

print(all_values_equal)  # Output: True

my_dict = {
    'tutorial': 5,
    'reference': 6,
    'com': 5
}

all_values_equal = True
first_value = list(my_dict.values())[0]

for value in my_dict.values():
    if value != first_value:
        all_values_equal = False
        break

print(all_values_equal)  # Output: False

• The code iterates through the values of the dictionary and sets the all_values_equal variable to False as soon as it finds a different value.
• break statement breaks out of the loop as soon as a difference is found.