Prerequisite: chr()
The following methods explain how a python list with alphabets in lexical(alphabetic) order can be generated dynamically using chr() method.
Approach:
The core of the concept in both methods is almost same, they only differ in implementation:
- Validate size of alphabet list(size=26).
- If size>26, change to 26.
- If size≤0, no meaning left to the function and to make it meaningful set size to 26.
- Use chr() to produce the list using any of following methods.
Method 1: Using loop
Python3
# function to get the list of alphabetsdef generateAlphabetListDynamically(size = 26): size = 26 if (size > 26 or size <= 0) else size # Empty list alphabetList = [] # Looping from 0 to required size for i in range(size): alphabetList.append(chr(65 + i)) # return the generated list return alphabetListalphabetList = generateAlphabetListDynamically()print('The alphabets in the list are:', *alphabetList) |
Output:
The alphabets in the list are: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Time Complexity: O(n), where n is length of alphabetList.
Auxiliary Space: O(n), where n is length of alphabetList.
Method 2: using list comprehension
Python3
def generateAlphabetListDynamically(size=26): size = 26 if (size > 26 or size <= 0) else size # Here we are looping from 0 to upto specified size # 65 is added because it is ascii equivalent of 'A' alphabetList = [chr(i+65) for i in range(size)] # returning the list return alphabetList# Calling the function to get the alphabetsalphabetList = generateAlphabetListDynamically()print('The alphabets in the list are:', *alphabetList) |
Output:
The alphabets in the list are: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Time Complexity: O(n)
Auxiliary Space: O(n)
Approach 3: Using the string library
This approach is simpler compared to the other two, as we don’t have to use any loop or list comprehension. Instead, we just use the string.ascii_uppercase constant, which returns a string containing all ASCII uppercase letters. Then, we just slice it to get the first size characters and convert it to a list.
Python3
import stringdef generateAlphabetListDynamically(size=26): size = 26 if (size > 26 or size <= 0) else size alphabetList = list(string.ascii_uppercase[:size]) return alphabetListalphabetList = generateAlphabetListDynamically()print('The alphabets in the list are:', *alphabetList) |
The alphabets in the list are: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Time Complexity: O(n)
Auxiliary Space: O(n)
