数组支持列表的索引方法

Question

我正在尝试利用 NumPy 完成数组支持列表的构建。这种特殊的方法给我带来了麻烦，我无法诊断问题。

def index(self, value, i=0, j=None):
    """Returns the index of the first instance of value encountered in
    this list between index i (inclusive) and j (exclusive). If j is not
    specified, search through the end of the list for value. If value
    is not in the list, raise a ValueError."""
    if j is None:
        j = self.size
    for idx in range(i, j):
        if self.data[idx] == value:
            return idx
    raise ValueError()

这是测试返回的内容：

self = [1, 2, 1, 2, 1, 1, 1, 2, 1], value = 2, i = 4, j = -1

    def index(self, value, i=0, j=None):
       
        if j is None:
            j = self.size
        for idx in range(i, j):
            if self.data[idx] == value:
                return idx
>       raise ValueError()
E       ValueError

arraylist.py:168: ValueError

Answer 1

def getindex(lst, value, i=0, j=None):

    #define j if j is None or j == -1
    j = len(lst)-1 if j == -1 or j is None else j

    #create a list with the value from i and j
    l = [lst[k] for k in range(i, j)]
    
    try:
        # get the index of the value
        idx = l.index(value)

        # Add i as you want to know the index in the original list
        idx = idx + i
        return idx

    except ValueError:
        return 'Value Error'
        

#for given values
lst =  [1, 2, 1, 2, 1, 1, 1, 2, 1]
value = 2
i = 4
j = -1
r = getindex(lst,value, i)
print(r) # output : 7

#If j is not specified
lst =  [1, 2, 1, 2, 1, 1, 1, 2, 1]
value = 2
i = 4
r = getindex(lst,value, i)
print(r) # output : 7

# If value not in the given lst
lst =  [1, 2, 1, 2, 1, 1, 1, 4, 1]
value = 2
i = 4
r = getindex(lst,value, i)
print(r) #output: Value Error