all() Function Python
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Overview
Python provides various built-in functions that are very useful in performing complex tasks. So when you have to check if all items in an iterable evaluate to True, don't forget to use the function Python. So basically, function Python accepts an iterable object and returns True if all the items in the passed iterable are True, else it returns False. The iterable objects could be lists, tuples, dictionaries, sets, strings, etc.
Syntax of all() Function in Python
The syntax of function Python is:
Parameters of all() Function in Python
The function Python takes only single parameter:
Iterable: Any iterable object such as lists, tuples, dictionaries, etc that contains elements.
Return value of Python all() Function
The function Python returns:
- True: If all the values in an iterable are True.
- False: If any value in an iterable is False.
If we have an empty iterable, this function returns true.
How does all() Function in Python Work?
The function searches for false elements. It iterates every element in an iterable object, and when it reaches the end, that means everything is fine so it will return true; else if it encounters any false value, it will return false and stop iterating. Let’s have a look at one basic example that will show you the usage of the function.
As you can see in the above examples: In example 1, the function Python iterates till the end and returns True because there is no False value.
In example 2, the function Python will stop at the index because 0 is False in a boolean context.
In example 3, the function Python will iterate till the end and will return True. Since the list is empty, it will print True.
Examples of all() Function Python
Example 1: How does all() Function Work for Lists?
Code:
Output:
Explanation: In the above code, as you can see,
We have created a list named l1, which has some numerical values. So when we use the function here, it will return True.
Then we created another list named l2. All the elements in the list l2 are False, so the function Python will generate a False boolean value. In l3, some elements are True while others are False. Because the list contains at least one false value, Python's function will return False. The last list(l4) is empty, so it will return True because there are no elements that are False in the list.
Example 2: How does all() Function Work for Tuples?
Code:
Output:
Explanation: Here, we have defined four tuples. Some tuples have all True values and some all False, and some contain at least one False value. And the last tuple consists of an empty value. The function will take all the specified values as an argument and will return the result corresponding to each tuple.
Example 3: How does all() Function Work for a Set?
Code:
Output:
Explanation: The function works the same for sets, as it works for lists and tuples.
Example 4: How does all() Function Work for a Dictionary?
Code:
Output:
Explanation: As we can see in the above code, we have a pair of keys and values in the dictionary. So, when we apply the function to the dictionary, the output is solely dependent on the keys. In the dictionary d2, if all the keys of the dictionary or the dictionary are empty, the function in Python will return True, and if any key is False in the dictionary, then it will return False, as you can see in the dictionary d2.
Example 5: How does all() Function Work for a String?
Code:
Output:
Explanation: The string is also an iterable object. When we pass a string to the function Python, then it behaves like a list. So, the string always returns True, and if the string is empty, then it will also return True.
Consider str2. You might think str2 has 0 and should return false. The answer is NO because string always keeps any number or string in ""(inverted comma), so the output will always be true.
Conclusion
Let's conclude our topic all() function Python by mentioning some of the important points:
- The function in Python returns True if all of the values in an iterable are True, and False if any of the values in an iterable are false.
- The function takes a single iterable object and performs the operations. The iterable objects could be lists, tuples, dictionaries, sets, strings, etc.
- The syntax of function Python is: all(iterable).
- The function in Python either returns True or False, based on conditions.