如何使用python加载libsvm文件（填充缺少的值）

Question

令v = [10：1，15：2，20：3]; （i = [0，1，2]列表中值的索引）

• n = 10 - (i + 1) = 10 - (0 + 1) = 9 ==> newV = [0, 0, 0, 0, 0, 0, 0, 0, 0, 1]
• n = 15 - (9 + i + 1) = 15 - (9 + 1 + 1) = 4 ==> newV =[0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 2]
• n = 20 - ( 9 + 4 + 2 + 1 ) = 20 - 16 = 4 ==> newV =[0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 2, 0, 0, 0, 0, 3]

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finalV = [0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 2, 0, 0, 0, 0, 3]`

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if __name__ == '__main__':
    v = ['1:1', '15:2', '30:3']
    previous_Idx = []
    newV = []
    for i in  range(0, len(v)):
      idx = int(v[i].split(':')[0])
      val = float(v[i].split(':')[-1])
      n = idx - (sum(previous_Idx) + i + 1)
      for _ in range(n):
         newV.append(0)
      previous_Idx.append(n)
      newV.append(val)
    print newV

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谢谢你的铅笔和纸。

Answer 1

您的问题中有一些不清楚的地方，但这是可能的解决方案

for line in open("file.txt", 'r').readlines():
    line = line.strip().split(" ")
    lineName = line.pop(0)
    arr = [0.0] * int(line[-1].split(":")[0])  # fills the array with zeros

    for element in line:
        index,value = element.split(":")
        arr[int(index)-1] = float(value)

    print lineName + " " + " ".join(map(str, arr))  # /questions/6507431