Python indices function

Introduction

In Python, strings are a very common and important data type. Strings provide many functions and methods for manipulating and processing text data. One useful method is the indices function, which is used to find the indices of all occurrences of a specified substring within a given string.

In this article, we will introduce the indices function in detail, provide sample code, and explain its functionality and purpose.

Syntax

The syntax of the

indices function is as follows:

def indices(string: str, substring: str) -> List[int]:
pass

string is a string representing the target string in which to search for a substring. substring is a string representing the substring to be searched.

The

indices function returns a list of integers containing the indices of all occurrences of the substring in the target string. If the substring does not exist in the target string, an empty list is returned.

Sample Code

Here is a sample code using the indices function:

def indices(string: str, substring: str) -> List[int]:
if substring not in string:
return []

indices_list = []
index = 0
while index < len(string):
if string[index:index+len(substring)] == substring:
indices_list.append(index)
index += len(substring)
else:
index += 1

return indices_list

# Example 1
string_1 = "abracadabra"
substring_1 = "a"
print(indices(string_1, substring_1))
# Output: [0, 3, 5, 7, 10]

# Example 2
string_2 = "Hello, world!"
substring_2 = "o"
print(indices(string_2, substring_2))
# Output: [4, 8]

# Example 3
string_3 = "Python is awesome"
substring_3 = "xyz"
print(indices(string_3, substring_3))
# Output: []

Parsing and Explanation

In the above code example, we define an indices function that takes two parameters: a string and a substring. The function first checks whether substring is contained in string. If not, an empty list is returned.

Then, we create an empty list, indices_list, to store the indices of where the substring occurs in the target string.

Next, we use a while loop to iterate through all the characters of the target string, string. In each loop iteration, we check whether a substring starting at the current index and equal to the length of the substring is equal to the substring itself. If a match is found, the current index is added to indices_list, and the index is updated to the next position to be checked, which is the current position plus the length of the substring. If a match is not found, the index is incremented by 1 and the next position is checked.

Finally, indices_list is returned, which contains the indices of all occurrences of the substring in the target string.

Below the sample code, we provide three examples to demonstrate the use of the indices function. In Example 1, we find the index of the substring "a" in the string "abracadabra". The result is [0, 3, 5, 7, 10], because "a" appears at indexes 0, 3, 5, 7, and 10. In Example 2, we find the index of the substring "o" in the string "Hello, world!". The result is [4, 8], because "o" appears at indexes 4 and 8. In Example 3, we search for the index of the substring "xyz" in the string "Python is awesome". The result is an empty list [] because "xyz" does not exist in the target string.

Summary

The indices function is very useful because it allows us to find the indices of all occurrences of a specified substring within a given string. We can use this function to process and manipulate text data, such as finding and replacing specific words or characters within a string.