Consecutive Character Grouping in Strings | CodeSignal Learn

Consecutive Character Grouping in Strings | CodeSignal Learn

Introduction

Hello there! Today, we’re going to delve into handling and manipulating strings in Python, a skill that is invaluable in many areas of programming. Specifically, we'll learn how to identify consecutive groups of equal characters in a string. Are you curious to know more and enhance your skills? Then let's get started!

Task Statement

In this lesson, our goal is to write a Python function that accepts a string as input and identifies all consecutive groups of identical characters within it. A group can be defined as a segment of the text where the same character is repeated consecutively. Your function should return a list of tuples. Each tuple will consist of the repeating character and the length of its repetition. For instance, if the input string is "aaabbcccaae", your function should output: [('a', 3), ('b', 2), ('c', 3), ('a', 2), ('e', 1)] . It's important to note that while processing the input string, we are interested only in alphanumeric characters (i.e., alphabets and digits), whether they are upper or lower case. Any other characters present won't factor into the formation of these groups. Are you ready to unravel how to accomplish this task? Let's dive in!

Solution Building, Step 1: Initialization

As is always the case when attempting to solve a problem, it's a good idea to take preliminary steps to establish our scope. First, we will initialize an empty list groups to store our results. We will also declare two variables, current_group_char and current_group_length, which will help us keep track of the current group's character and the length of its consecutive sequence. Python def solution(s): groups = [] current_group_char = None current_group_length = 0

Step 2: Loop Through the String

With the setup in place, we now arrive at the main event: processing the input string. For this, we loop through the string to examine each character. At each step, we also need to verify whether the character is alphanumeric, as that's all we're interested in. Python def solution(s): groups = [] current_group_char = None current_group_length = 0 for char in s: if char.isdigit() or char.isalpha():

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Step 3: Identify the Groups

During our loop, if a character is the same as current_group_char, it means that the group is continued, and we merely increment current_group_length . However, if the character is different from current_group_char, it signifies the start of a new group. At the start of a new group, we append the tuple (current_group_char, current_group_length) to groups, and then update current_group_char and current_group_length with the new character and 1, respectively. def solution(s): groups = [] current_group_char = None current_group_length = 0 for char in s: if char.isdigit() or char.isalpha(): if char == current_group_char: current_group_length += 1 else: if current_group_char is not None: groups.append((current_group_char, current_group_length)) current_group_char = char current_group_length = 1

Step 4: Wrap Up

After ending the loop, we need to be aware of the potential for a leftover group that has not yet been added to groups . This can happen because we only add a group to groups when we identify a new group. To ensure we don't miss any groups, we make a final check on current_group and, if necessary, add it to groups . def solution(s): groups = [] current_group_char = None current_group_length = 0 for char in s: if char.isdigit() or char.isalpha(): if char == current_group_char: current_group_length += 1 else: if current_group_char is not None: groups.append((current_group_char, current_group_length)) current_group_char = char current_group_length = 1 if current_group_char is not None: groups.append((current_group_char, current_group_length)) return groups

Python

def solution(s):
    groups = []
    current_group_char = None
    current_group_length = 0

    for char in s:
        if char.isdigit() or char.isalpha():
            if char == current_group_char:
                current_group_length += 1
            else:
                if current_group_char is not None:
                    groups.append((current_group_char, current_group_length))
                current_group_char = char
                current_group_length = 1

Python

def solution(s):
    groups = []
    current_group_char = None
    current_group_length = 0

    for char in s:
        if char.isdigit() or char.isalpha():
            if char == current_group_char:
                current_group_length += 1
            else:
                if current_group_char is not None:
                    groups.append((current_group_char, current_group_length))
                current_group_char = char
                current_group_length = 1
    if current_group_char is not None:
        groups.append((current_group_char, current_group_length))
    
    return groups