How to Check for Multiple Values in a Python List: all() and any()

Often, you need to determine if all or any of a set of values are present in a Python list.

This guide explains how to efficiently perform these checks using the built-in all() and any() functions, along with list comprehensions and generator expressions. We'll also briefly cover alternative approaches using sets and for loops.

Checking if ALL Values are in a List with all()

The all() function is the most Pythonic and generally the most efficient way to check if all elements of an iterable are True (or, equivalently, if none of them are False). We combine all() with a generator expression or a list comprehension that performs the membership check (in).

Using a Generator Expression

my_list = ['one', 'two', 'three', 'four', 'five']
multiple_values = ['one', 'two', 'three']

if all(value in my_list for value in multiple_values):
    print('All of the values are in the list')  # This will print
else:
    print('Not all of the values are in the list')

print(all(value in my_list for value in multiple_values))  # Output: True

• value in my_list: This is the core check. The in operator tests for membership (is value present in my_list?).
• for value in multiple_values: This iterates over each value in the multiple_values list.
• (value in my_list for value in multiple_values): This is a generator expression. It efficiently produces a sequence of boolean values (True/False) without creating an intermediate list.
• all(...): The all() function checks if all of the boolean values produced by the generator expression are True.

Using a List Comprehension

You can use a list comprehension, but it's less memory-efficient:

my_list = ['one', 'two', 'three', 'four', 'five']
multiple_values = ['one', 'two', 'three']
if all([value in my_list for value in multiple_values]):  # List comprehension
    # ...

• The [value in my_list for value in multiple_values] will first create a list with all the boolean results of the check.
• The all() method will then check if all of the boolean values from the list are True.
• This creates an unnecessary intermediate list. The generator expression is generally preferred because it avoids creating this extra list.

Checking if Any Value is in a List with any()

The any() function is the counterpart to all(). It returns True if at least one element of an iterable is True.

my_list = ['one', 'two', 'three']
multiple_values = ['four', 'five', 'three']

if any(item in my_list for item in multiple_values):
    print('At least one of the values is in the list')  # This will be printed
else:
    print('None of the values are in the list')

• The generator expression (item in my_list for item in multiple_values) checks each item from multiple_values for membership in my_list.
• any(...) returns True as soon as it finds any value that's present, and False otherwise.

Getting the Matching Value (if any)

If you need to know which value was found, you can use the walrus operator (:=) within the generator expression:

my_list = ['one', 'two', 'three']
multiple_values = ['four', 'five', 'three']

if any((match := item) in my_list for item in multiple_values):
    print('At least one of the values is in the list')
    print(match)  # Output: three (the *last* matching value)
else:
    print('None of the values are in the list')

• (match := item): This uses the "walrus operator" (assignment expression) to assign the current item to the variable match within the generator expression.
• Important: match will hold the last value from multiple_values that was found in my_list. If multiple values match, you only get the last one. If no values match, match will not be defined.

Alternative: Using Sets (for all() checks)

For checking if all values are present, you can use set operations. This can be very efficient, especially if multiple_values is large:

my_list = ['one', 'two', 'three', 'four', 'five']
multiple_values = ['one', 'two', 'three']

if set(multiple_values).issubset(my_list):  # Or: set(multiple_values) <= set(my_list)
    print('All of the values are in the list')  # This will print
else:
    print('Not all of the values are in the list')

• set(multiple_values): Converts multiple_values to a set.
• .issubset(my_list): Checks if all elements of the set are present in my_list. This is equivalent to the set operation <=.
• This is generally faster than the all() approach with in if multiple_values has many elements, because set lookups (in with a set) are very fast (O(1) on average).

Alternative: Using a for Loop (Less Efficient)

You can use a for loop, but it's generally less efficient and less readable than the other methods:

my_list = ['one', 'two', 'three', 'four', 'five']
multiple_values = ['one', 'two', 'three']

multiple_in_list = True  # Assume all are present initially

for value in multiple_values:
    if value not in my_list:
        multiple_in_list = False
        break  # Exit the loop as soon as one is missing

print(multiple_in_list)  # Output: True

• This approach requires explicit looping and a flag variable (multiple_in_list). It's more verbose and less efficient than using all() or set operations. Avoid this unless you have a very specific reason to do so.