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POExtracting data from nested tuples
 

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  1. POExtracting data from nested tuples
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    <p>For an application I'm working on I need to create lists from nested tuples, representing the data contained in each branch. </p> <p>For reference the tuples represent a Huffman tree, an example is:</p> <pre><code>tree = (1.0, (0.5, (0.25, (0.125, 'd'),(0.125, 'c')), (0.25, 'b')), (0.5,'a')) </code></pre> <p>This was created from a Huffman routine with the following probabilities:</p> <pre><code>a:0.5, b:0.25, c:0.125, d:0.125 </code></pre> <p>I would like to out put a list which looks like </p> <pre><code>[['a'],['b','c','d']] </code></pre> <p>I've tried the following code:</p> <pre><code>def makeList(tree): if len(tree) == 2: return [tree[0]] else: rightlist = [] leftlist = [] right = list(tree[1]) left = list(tree[2]) for i in range(1, len(right)): rightlist.append(right[i]) for i in range(1, len(left)): leftlist.append(left[i]) return [rightlist, leftlist] </code></pre> <p>However this returns</p> <pre><code>[['a'],[(0.25, (0.125, 'd'),(0.125,'c')),(0.25,'b')] </code></pre> <p>Which isn't quite what I want. </p> <p>How could I go about modifying my code above to produce the output I want?</p> <p><strong>EDIT</strong></p> <p>I have produced some code which given a balanced input: </p> <pre><code>('a',0.25), ('b', 0.25), ('c', 0.25), ('d',0.25) </code></pre> <p>produces the output I want:</p> <pre><code>[['a','b'], ['c','d']] def makeList(tree): if len(tree) == 2: print("I'm in here") return [tree[1]] else: right = tree[1] left = tree[2] rightlist = [] leftlist = [] for i in range(0, len(right)): if type(right[i]) == tuple: print('right: ' + str(right[i])) rightlist.append(right[i][1]) for i in range(0, len(left)): if type(left[i]) == tuple: print('left: ' + str(left[i])) leftlist.append(left[i][1]) return [rightlist, leftlist] </code></pre> <p>However, it fails on the following inputs (output below):</p> <pre><code>exampleData = [(0.5, 'a'), (0.5,'b')] [[],[[]] exampleData = [(0.5, 'a'), (0.25,'b'), (0.25,'c')] [[],['b'.'c']] exampleData = [(0.5,'a'), (0.25,'b'), (0.125,'c'), (0.125,'d')] [[]],['b',(0.125, 'd')]] </code></pre> <p>However, the gold-standard test that this needs to pass is creating these lists for random trees:</p> <pre><code>probs = np.random.dirichlet([1]*4).tolist() indices = range(0,4) exampleData = zip(probs, indices) huffTree = makeHuffmanTree(exampleData) groups = makeLists(groups) </code></pre>
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    1. USTom Kealy
    1. USTom Kealy
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      1. USGreg Whittier
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    1. COIs this the actual code? I thought it was len not length and the for loop needed colons on the end
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      1. USdoctorlove
    2. COCould you explain how you determined that you want the output `[['a'],['b','c','d']]`? Why is `b` in the same list as `c` and `d`, when it has a different probability?
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      1. USKevin
    3. CO@doctorlove yes, of course. Have added the colons and removed the 1st length.
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      1. USTom Kealy
 

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