Aditya
42 lines
1.2 KiB
Python
42 lines
1.2 KiB
Python
import heapq
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import itertools
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def build_huffman_tree(freq):
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heap = []
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counter = itertools.count() # unique sequence count
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for ch, weight in freq.items():
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heap.append([weight, next(counter), [ch]]) # add counter as second element
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heapq.heapify(heap)
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while len(heap) > 1:
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low = heapq.heappop(heap)
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high = heapq.heappop(heap)
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combined_weight = low[0] + high[0]
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combined_node = [low[2], high[2]]
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heapq.heappush(heap, [combined_weight, next(counter), combined_node])
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return heap[0]
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def assign_codes(node, prefix="", codebook={}):
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# node is [char] for leaf, or [left, right] for internal node
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if len(node) == 1 and isinstance(node[0], str):
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codebook[node[0]] = prefix
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else:
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assign_codes(node[0], prefix + "0", codebook)
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assign_codes(node[1], prefix + "1", codebook)
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return codebook
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def huff_en(txt):
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freq = {}
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for c in txt:
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freq[c] = freq.get(c, 0) + 1
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root = build_huffman_tree(freq)
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codes = assign_codes(root[2]) # Note: root[2] because of tie-breaker
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print("Huffman Codes:")
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for ch in sorted(codes):
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print(f"{ch}: {codes[ch]}")
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txt="abbbbbbcccddddddddee"
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huff_en(txt) |