Python program to check if characters of all string elements are in lexicographic order

Lexical order refers to the order of characters or strings based on dictionary or alphabetical order. Characters are arranged in lexical order the same way they are arranged in a dictionary. The comparison is done based on the numerical value of the characters in the respective character set (such as ASCII or Unicode).

In lexical order, characters are compared from left to right based on their ASCII or Unicode values. Characters with lower ASCII or Unicode values ​​precede characters with higher values. For example, in ASCII order, "a" comes before "b", "b" comes before "c", and so on.

When comparing strings, lexical order is determined by comparing the corresponding characters of the string from left to right. A string is considered lexically larger if its first character is greater than the corresponding character of another string. If the first characters are the same, the second characters are compared, and so on until a difference is found or a string ends.

There are multiple ways to check whether the characters of all string elements are in lexical order.

Use all() function

The

all() function is a built-in Python function that returns True if all elements in the iterable are considered True, otherwise it returns False. It takes iterable as a parameter and evaluates each element in the iterable for truthfulness.

The following are key points similar to how the all() function works.

• It takes an Iterable as its argument, such as a list, tuple, set or any other iterable object.

• It iterates over each element in the iterable.

• This function returns True if all elements in the Boolean context are considered True.

• This function returns False if any element is considered False in a Boolean context.

• If the iterable is empty, this function will return True because there are no elements to calculate.

Example

In this method, we use list comprehension and all() function to iterate over the list of strings. The all() function returns True only if all elements in the iterable are True. In list comprehension, we compare each string with the next string using

def check_lexical_order(strings):
   return all(strings[i] <= strings[i+1] for i in range(len(strings)-1))
words = ['apple', 'banana', 'cherry', 'date']
result = check_lexical_order(words)
print(result)

Output

True

Use sorted() function

The sorted() function is a built-in Python function that returns a new sorted list from the elements of an iterable. It accepts an iterable object as argument and returns a new list containing the elements of the iterable object in ascending order.

The following are the key points of how the sorted() function works.

• It accepts an iterable object as its first argument, such as a list, tuple, set or any other iterable object.

• It creates a new list by iterating over the elements of an iterable.

• It compares elements using the default order or a custom key function (if provided).

• It returns a new list with elements sorted in ascending order.

Example

In this method, we use the sorted() function to create a new list sorted_strings, which contains the strings sorted in lexical order. We then compare this sorted list with the original list of strings using the == operator. If the two lists are equal, it means that the characters of all string elements are in lexical order.

def check_lexical_order(strings):
   sorted_strings = sorted(strings)
   return sorted_strings == strings
words = ['apple', 'banana', 'cherry', 'date']
result = check_lexical_order(words)
print(result)

Output

True

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