⭐Summary: To get the first “N” characters of a string slice, the string from the starting index until the Nth character using Python’s slice notation.
Minimal Example
text = "akjvdkavkjsdvkja" # Get first 3 characters print(text[:3]) # OUTPUT: akj
Problem Formulation
📜Problem: Given a string. How will you get the first “N” characters of the string?
Example 1
In the following example, you just have to extract the first 5 characters from the given string.
# INPUT text = 'abcdefghijklmnopqr' n = 5 # OUTPUT abcde
Example 2
In the following example, you first have to split the string and get the words/substrings out of it and then extract the first three characters from each substring.
# Input text = "eagdef-ernopqr-essvwxyz" # Output eagerness
Solution: Split and Slice the String
Approach to Solve Example 1: Slice the string using square bracket notation and extract the required number of characters using their indices.
Since we need the first 5 characters, you can simply slice the string starting from 0 until 5. This means the start value is 0 while the stop value is 5.
Code:
text = 'abcdefghijklmnopqr' n = 5 print(text[0:n]) # abcde
Approach to Solve Example 2: You have to go a step further to solve the second scenario. Here, you have to first split the string using the given delimiter (“-“) which will create a list of substrings. Now in order to extract the first three characters from each substring simply iterate through each item of the list using a for loop and slice out the first three characters from each element in each iteration with the help of slice notation.
text = "eagdef-ernopqr-essvwxyz"
res = text.split('-')
for i in res:
print(i[:3], end='')
# eagerness
Graphical Illustration:
Note:
Slicing is a concept to carve out a substring from a given string. Use slicing notation s[start:stop:step] to access every step-th element starting from index start (included) and ending in index stop (excluded). All three arguments are optional, so you can skip them to use the default values (start=0, stop=len(lst), step=1). For example, the expression s[2:4] from string 'hello' carves out the slice 'll' and the expression s[:3:2] carves out the slice 'hl'.
Related Video:
Related Read: Introduction to Slicing in Python
Bonus Questions
🍎Qs 1: How to Split a String After Every N Characters?
Solution: One of the easiest ways to split a string after every n character is to use a list comprehension to and slice the string accordingly to extract every n character of the given string and store them in a list. The items of this list represent the required split substrings.
Example:
given_string = 'abcdef' n = 3 print([(given_string[i:i+n]) for i in range(0, len(given_string), n)]) # OUTPUT: ['abc', 'def']
Read More: Python | Split String Every “N” Characters
🍎Qs 2: How to Split a String and Get the Nth Element?
Solution: Split the string normally at the occurrence of the given delimiter using the split method. To extract the required element from the list use its index within square brackets.
Example
text = "Welcome to the world of Python!"
res = text.split()
print("Split substrings: ", res)
print("Required Element: ", res[3])
# OUTPUT:
# Split substrings: ['Welcome', 'to', 'the', 'world', 'of', 'Python!']
# Required Element: world
Read More: Python | Split String Get Element
🍎Qs 3: How to Split a String and Get First N elements?
Approach: Split the string using the split function and the given delimiter. Then extract the first “N” characters from the split list of substrings using their index.
Example:
text = 'abc-efg-xyz-lmn-pqr'
res = text.split('-')
for i in range(3):
print(res[i], end=" ")
# abc efg xyz
🍎Qs 4: How to Split a String and Get the Last “N” Elements?
Solution: Split the string using Python’s built-in split method and the given separator. To extract the last three elements from this split list, iterate in a reverse range starting from -3 until 0. This will allow you to grab the last three elements from the list using their negative indices.
Example:
text = 'abc-efg-xyz-lmn-pqr'
res = text.split('-')
for i in range(-3, 0):
print(res[i], end=" ")
# xyz lmn pqr
Conclusion
I hope the questions and their solutions discussed in this article have helped you. Please subscribe and stay tuned for more interesting solutions and discussions in the future.
Happy coding! 🙂
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