Python program to extract only the numbers from a list which have some specific digits

When you need to extract numbers from a list that contain only specific digits, you can use list comprehension with the all() function. This technique filters numbers by checking if every digit in each number exists in your allowed digits set.

Syntax

result = [num for num in numbers if all(int(digit) in allowed_digits for digit in str(num))]

Example

Let's extract numbers that contain only the digits 2, 3, 4, and 5 ?

numbers = [3345, 2345, 1698, 2475, 1932]

print("The original list is:")
print(numbers)

allowed_digits = [2, 3, 4, 5]

result = [num for num in numbers if all(int(digit) in allowed_digits for digit in str(num))]

print("Numbers containing only digits 2, 3, 4, 5:")
print(result)

The original list is:
[3345, 2345, 1698, 2475, 1932]
Numbers containing only digits 2, 3, 4, 5:
[3345, 2345]

How It Works

The solution works by:

• Converting each number to string: str(num) allows iteration over individual digits

• Checking each digit: int(digit) in allowed_digits verifies if the digit is allowed

• Using all(): Returns True only if every digit passes the check

• List comprehension: Builds the result list with numbers that satisfy the condition

Different Digit Sets

You can use any set of allowed digits ?

numbers = [123, 456, 789, 147, 258, 369]

# Only digits 1, 2, 3
allowed_digits = [1, 2, 3]
result = [num for num in numbers if all(int(digit) in allowed_digits for digit in str(num))]

print("Numbers with only digits 1, 2, 3:")
print(result)

Numbers with only digits 1, 2, 3:
[123]

Using Set for Better Performance

For larger digit sets, use a set for faster lookup ?

numbers = [1234, 5678, 9012, 3456, 7890]
allowed_digits = {0, 1, 2, 3, 4, 5, 6}  # Using set

result = [num for num in numbers if all(int(digit) in allowed_digits for digit in str(num))]

print("Numbers with only digits 0-6:")
print(result)

Numbers with only digits 0-6:
[1234, 3456]

Conclusion

Use list comprehension with all() to filter numbers containing only specific digits. Convert numbers to strings for digit-by-digit checking. Consider using sets for better performance with larger digit collections.