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Python: Decode a run-length encoded given list

Python List: Exercise - 77 with Solution

Run-length encoding (RLE) is a form of lossless data compression in which runs of data (sequences in which the same data value occurs in many consecutive data elements) are stored as a single data value and count, rather than as the original run.

Write a Python program to decode a run-length encoded given list.

Sample Solution:

Python Code:

def decode(alist):
    def aux(g):
        if isinstance(g, list):
            return [(g[1], range(g[0]))]
        else:
            return [(g, [0])]
    return [x for g in alist for x, R in aux(g) for i in R]
n_list = [[2, 1], 2, 3, [2, 4], 5, 1]
print("Original encoded list:") 
print(n_list)
print("\nDecode a run-length encoded said list:")
print(decode(n_list))

Sample Output:

Original encoded list:
[[2, 1], 2, 3, [2, 4], 5, 1]

Decode a run-length encoded said list:
[1, 1, 2, 3, 4, 4, 5, 1]

Flowchart:

Flowchart: Decode a run-length encoded given list.

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Previous: Write a Python program to create a list reflecting the run-length encoding from a given list of integers or a given list of characters.
Next: Write a Python program to split a given list into two parts where the length of the first part of the list is given.

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Python: Tips of the Day

Floor Division:

When we speak of division we normally mean (/) float division operator, this will give a precise result in float format with decimals.

For a rounded integer result there is (//) floor division operator in Python. Floor division will only give integer results that are round numbers.

print(1000 // 300)
print(1000 / 300)

Output:

3
3.3333333333333335