Run Length Encoding in Python

In this tutorial, we are going to learn how to create a run-length encoding in Python. Given a string return a new string containing char and frequency.

For example, the string tutorialspoint will be encoded as t3u1o2r1i2a1l1s1p1n1. The order is every char+frequency. Join all of them and return. See the steps below to write the program.

• Write the function with the name run_length_encoding.

• Initialize a dictionary with OrderedDict to get an initial count of chars as 0.

• Iterate over every character of the string and increment the count in the dictionary.

• Join all the chars and their frequencies. And print it.

• Initialize the strings and invoke the function.

Example

Let's see the code for the above text.

# importing the collections
import collections
# function
def run_length_encoding(string):
   # initialzing the count dict
   count_dict = collections.OrderedDict.fromkeys(string, 0)
   # iterating over the string
   for char in string:
      # incrementing the frequency
      count_dict[char] += 1
   # initializing the empty encoded string
   encoded_string = ""
   # joining all the chars and their frequencies
   for key, value in count_dict.items():
      # joining
      encoded_string += key + str(value)
      # printing the encoded string
print(encoded_string)
# initializing the strings
string = "tutorialspoint"
# invoking the function
run_length_encoding(string)
# another string
string = "aaaaaabbbbbccccccczzzzzz"
run_length_encoding(string)

Output

If you run the above code, you will get the following output.

t3u1o2r1i2a1l1s1p1n1
a6b5c7z6

Conclusion

If you have any doubts in the tutorial, mention them in the comment section.

Hafeezul Kareem

Updated on: 12-Feb-2020

1K+ Views

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