Run Length Encoding in Python
Given an input string, write a function that returns the Run Length Encoded string for the input string.
For example, if the input string is ‘wwwwaaadexxxxxx’, then the function should return ‘w4a3d1e1x6’.
Examples:
Input : str = 'wwwwaaadexxxxxx' Output : 'w4a3d1e1x6'
This problem has existing solution please refer Run Length Encoding link. Here we will solve this problem quickly in python using OrderedDict. Approach is very simple, first we create a ordered dictionary which contains characters of input string as key and 0 as their default value, now we run a loop to count frequency of each character and will map it to it’s corresponding key.
# Python code for run length encodingfrom collections import OrderedDictdef runLengthEncoding(input): # Generate ordered dictionary of all lower # case alphabets, its output will be # dict = {'w':0, 'a':0, 'd':0, 'e':0, 'x':0} dict=OrderedDict.fromkeys(input, 0) # Now iterate through input string to calculate # frequency of each character, its output will be # dict = {'w':4,'a':3,'d':1,'e':1,'x':6} for ch in input: dict[ch] += 1 # now iterate through dictionary to make # output string from (key,value) pairs output = '' for key,value in dict.items(): output = output + key + str(value) return output # Driver functionif __name__ == "__main__": input="wwwwaaadexxxxxx" print (runLengthEncoding(input)) |
Output:
'w4a3d1e1x6'
Another code:
def encode(message): encoded_message = "" i = 0 while (i <= len(message)-1): count = 1 ch = message[i] j = i while (j < len(message)-1): if (message[j] == message[j+1]): count = count+1 j = j+1 else: break encoded_message=encoded_message+str(count)+ch i = j+1 return encoded_message #Provide different values for message and test your programencoded_message=encode("ABBBBCCCCCCCCAB")print(encoded_message) |
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