Python | Ways to initialize list with alphabets
Last Updated :
13 Sep, 2022
While working with Python lists, sometimes we wish to initialize the list with the English alphabet a-z or A-Z. This is an essential utility in competitive programming and also in certain applications. Let’s discuss various methods to achieve this using Python.
The most pythonic and latest way to perform this particular task. Using this new inbuilt function will internally handle the coding part providing a useful shorthand for the user.
Note: You can use lowercase instead of uppercase to generate lower alphabets.
Python3
import string
test_list = []
test_list = list (string.ascii_uppercase)
print ( "List after insertion : " + str (test_list))
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Output :
List after insertion : [‘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’]
Initialize the list with alphabets using a naive method
The most general method that comes to our mind is using the brute force method of running a Python loop till 26 and incrementing it while appending the letters in the list. Refer to ASCII Table for more.
Python3
test_list = []
print ( "Initial list : " + str (test_list))
alpha = 'a'
for i in range ( 0 , 26 ):
test_list.append(alpha)
alpha = chr ( ord (alpha) + 1 )
print ( "List after insertion : " + str (test_list))
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Output :
Initial list : []
List after insertion : [‘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’]
Initialize the list with alphabets using list comprehension
This is a method similar to the above method, but rather a shorthand for the naive method as it uses the list comprehension technique to achieve the task.
Python3
test_list = []
print ( "Initial list : " + str (test_list))
test_list = [ chr (x) for x in range ( ord ( 'a' ), ord ( 'z' ) + 1 )]
print ( "List after insertion : " + str (test_list))
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Output :
Initial list : []
List after insertion : [‘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’]
Initialize the list with alphabets using a map()
Using a map() is an elegant way to perform this particular task. It type casts the numbers in a range to a particular data type, char in this case, and assigns them to the list.
Python3
test_list = []
print ( "Initial list : " + str (test_list))
test_list = list ( map ( chr , range ( 97 , 123 )))
print ( "List after insertion : " + str (test_list))
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Output :
Initial list : []
List after insertion : [‘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’]
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