In this tutorial, we are going to learn how to find all duplicate values in a string. We can do it in different ways in Python. Let's explore them one by one.
The aim of the program we are going to write is to find the duplicate characters present in a string. For example, we have a string tutorialspoint the program will give us t o i as output. In simple words, we have to find characters whose count is greater than one in the string. Let's see.
Scratch Programs
Writing programs without using any modules. We can use different methods of Python to achieve our goal. First, we will find the duplicate characters of a string using the count method. Let's see the procedure first.
- Initialize a string.
- Initialize an empty list
- Loop over the string.
- Check whether the char frequency is greater than one or not using the count method.
If greater than one check whether it's present in the list or not. If not present append to the list
- Print the characters
Example
## initializing string string = "tutorialspoint" ## initializing a list to append all the duplicate characters duplicates = [] for char in string: ## checking whether the character have a duplicate or not ## str.count(char) returns the frequency of a char in the str if string.count(char) > 1: ## appending to the list if it's already not present if char not in duplicates: duplicates.append(char) print(*duplicates)
If you run the above program, you will get the following results.
Output
t o i
Now we will find the duplicate characters of string without any methods. We are going to use the dictionary data structure to get the desired output. Let's see the procedure first.
- Initialize a string.
- Initialize an empty dictionary
- Loop over the string.
- Check whether the char is already present in the dictionary or not
- Initialize the count of the char to 1
Increase the count
Example
## initializing string
string = "tutorialspoint"
## initializing a dictionary
duplicates = {}
for char in string:
## checking whether the char is already present in dictionary or not
if char in duplicates:
## increasing count if present
duplicates[char] += 1
else:
## initializing count to 1 if not present
duplicates[char] = 1
for key, value in duplicates.items():
if value > 1:
print(key, end = " ")
print()If you run the above program,
Output
t o i