Given a string (may contain both characters and digits), write a Python program to remove the numeric digits from string. Let’s discuss the different ways we can achieve this task.
Method #1: Using join and isdigit()
Python3
# Python code to demonstrate# how to remove numeric digits from string# using join and isdigit# initialising stringini_string = "Geeks123for127Lazyroar"# printing initial ini_stringprint("initial string : ", ini_string)# using join and isdigit# to remove numeric digits from stringres = ''.join([i for i in ini_string if not i.isdigit()])# printing resultprint("final string : ", res) |
initial string : Geeks123for127Lazyroar final string : GeeksforLazyroar
Time Complexity: O(n), where n is the length of the given string.
Auxiliary Space: O(n)
Method #2: Using translate and digits
Python3
# Python code to demonstrate# how to remove numeric digits from string# using translatefrom string import digits# initialising stringini_string = "Geeks123for127Lazyroar"# printing initial ini_stringprint("initial string : ", ini_string)# using translate and digits# to remove numeric digits from stringremove_digits = str.maketrans('', '', digits)res = ini_string.translate(remove_digits)# printing resultprint("final string : ", res) |
initial string : Geeks123for127Lazyroar final string : GeeksforLazyroar
Time Complexity: O(n), where n is the length of the input string “ini_string”. The reason is that the translate function is applied only once to the input string “ini_string”.
Auxiliary Space: O(1), as it only uses a constant amount of extra memory to store the removed digits and the result string.
Method #3: Using filter and lambda
Python3
# Python code to demonstrate# how to remove numeric digits from string# using filter and lambda# initialising stringini_string = "akshat123garg"# printing initial ini_stringprint("initial string : ", ini_string)# using filter and lambda# to remove numeric digits from stringres = "".join(filter(lambda x: not x.isdigit(), ini_string))# res = ini_string# printing resultprint("final string : ", str(res)) |
initial string : akshat123garg final string : akshatgarg
Time Complexity: O(n), where n is the length of the initial string “ini_string”.
Auxiliary Space: O(n), as the filter function creates a new string “res” which is of length n. The variable “res” is stored in memory, hence the space complexity is O(n).
Method#4 Using join() and isalpha()
Python3
# Python code to demonstrate# how to remove numeric digits from string# using join and isalpha# initialising stringstr1 = "Geeks123for127Lazyroar"# printing initial ini_stringprint("initial string : ", str1)# using join and isalpha# to remove numeric digits from stringstr2 = "".join(x for x in str1 if x.isalpha())# printing resultprint("final string : ", str2) |
initial string : Geeks123for127Lazyroar final string : GeeksforLazyroar
Time Complexity: O(n), where n is the length of the string. This is because the code loops through each character in the string and performs a simple check for each character.
Auxiliary Space: O(n), where n is the length of the final string after removing numeric digits. This is because a new string of size n is created as the result of removing numeric digits from the original string.
Method#5: Using loop and in
Python3
# Python code to demonstrate# how to remove numeric digits from string# using loop and in# initialising stringstr1 = "Geeks123for127Lazyroar"# printing initial ini_stringprint("initial string : ", str1)# using loop and in# to remove numeric digits from stringnum = "1234567890"str2 = ""for i in str1: if i not in num: str2+=i# printing resultprint("final string : ", str2) |
initial string : Geeks123for127Lazyroar final string : GeeksforLazyroar
Time complexity: O(n), where n is the length of the string. The loop iterates through each character of the string once.
Auxiliary space complexity: O(n), where n is the length of the string. The str2 variable is created to store the final string without numeric digits, which is the same length as the original string.
Method #6: Using ord() function
Python3
# Python code to demonstrate# how to remove numeric digits from string# using loop and in# initialising stringstr1 = "Geeks123for127Lazyroar"# printing initial ini_stringprint("initial string : ", str1)# using loop and in# to remove numeric digits from stringstr2=""for i in str1: if(not ord(i) in range(48,58)): str2+=i# printing resultprint("final string : ", str2) |
initial string : Geeks123for127Lazyroar final string : GeeksforLazyroar
Time complexity: O(n), where n is the length of the input string ‘str1’.
Auxiliary space: O(n), where n is the length of the input string ‘str1’.
Method #7: Using re
One approach to remove numeric digits from a given string is to use a regular expression to match and remove the digits. This can be done using the re module in Python.
Here is an example of how this can be done:
Python3
import re# Initialize the stringini_string = "Geeks123for127Lazyroar"# Print the initial stringprint("initial string : ", ini_string)# Use a regular expression to remove the digitsres = re.sub(r'\d', '', ini_string)# Print the resultprint("final string : ", res)#This code is contributed by Edula Vinay Kumar Reddy |
initial string : Geeks123for127Lazyroar final string : GeeksforLazyroar
Time Complexity: O(n), where n is the length of the string, as it needs to iterate through the entire string to remove the digits.
Auxiliary Space: O(n), as it only requires memory to store the result.
Method #8: Using replace() method
Python3
# Python code to demonstrate# how to remove numeric digits from string# initialising stringini_string = "Geeks123for127Lazyroar"# printing initial ini_stringprint("initial string : ", ini_string)# to remove numeric digits from stringfor i in "0123456789": ini_string=ini_string.replace(i,"") # printing resultprint("final string : ", ini_string) |
initial string : Geeks123for127Lazyroar final string : GeeksforLazyroar
Time Complexity: O(n), where n is the length of the string, as it needs to iterate through the entire string to remove the digits.
Auxiliary Space: O(n), as it only requires memory to store the result.
Method #9 : Using re.match()
Approach
- Initiate a for loop to traverse ini_string, create an empty string res
- Append the characters which are not numeric to res (to check numeric or not use regular expression ‘^[0-9]+$’ and re.match() method)
- Display res
Python3
import re# Initialize the stringini_string = "Geeks123for127Lazyroar"# Print the initial stringprint("initial string : ", ini_string)# Use a regular expression to remove the digitsres=""for i in ini_string: if not re.match('^[0-9]+$', i): res+=i# Print the resultprint("final string : ", res) |
initial string : Geeks123for127Lazyroar final string : GeeksforLazyroar
Time Complexity: O(n), where n is the length of the string, as it needs to iterate through the entire string to remove the digits.
Auxiliary Space: O(n), as it only requires memory to store the result.
