数组 PYTHON 中的 IndexError

Question

我想用 Python 编写这个 C# 函数，不幸的是我有这个 ERROR: IndexError: list assignment index out of range in Population.BinaryX.insert([i][j], dec) 行。谁能告诉我如何解决这个问题？！我做错了什么？

C# 代码：

public class Population
    {
        public float[] CodedX = new float[20];
        public float[,] BinaryX = new float[10, 8];
    }

private void BinaryTranslating()
        {
            int dec;
            int j = 0;
            for (var i = 0; i < 10; i++)
            {
                while (Population.CodedX[i] > 1 & j < 8)
                {
                    dec = (int)Population.CodedX[i] % 2;
                    Population.BinaryX[i, j] = dec;
                    Population.CodedX[i] /= 2;
                    j++;
                }
                j = 0;
            }
        }

 private void DecimalTranslating()
        {
            for (var i = 0; i < 10; i++)
            {
                Population.CodedX[i] = Population.BinaryX[i, 7] * 128 + Population.BinaryX[i, 6] * 64 + 
                                       Population.BinaryX[i, 5] * 32 + Population.BinaryX[i, 4] * 16 + 
                                       Population.BinaryX[i, 3] * 8 + Population.BinaryX[i, 2] * 4 + 
                                       Population.BinaryX[i, 1] * 2 + Population.BinaryX[i, 0];

            }
        }

Python 代码：

class Population:
CodedX = []
BinaryX = [[], []]

class Application:
@staticmethod
    def binary_translating():
        j = 0
        for i in range(10):
            while Population.CodedX[i] > 1 & j < 8:
                dec = int(Population.CodedX[i]) % 2
                Population.BinaryX.insert([i][j], dec)
                Population.CodedX[i] /= 2
                j += 1
            j = 0

@staticmethod
    def decimal_translating():
        for i in range(10):
            new_item = Population.BinaryX[i][7] * 128 + Population.BinaryX[i][6] * 64 + Population.BinaryX[i][5] * 32 +\
                       Population.BinaryX[i][4] * 16 + Population.BinaryX[i][3] * 8 + Population.BinaryX[i][2] * 4 +\
                       Population.BinaryX[i][1] * 2 + Population.BinaryX[i][0]
            Population.CodedX.insert(i, new_item)

Answer 1

考虑Population.BinaryX.insert([i][j], dec) 中的[i][j] 表达式。该表达式创建一个包含 i 值的 1 项列表，然后尝试从该列表中获取 jth 项。

>>> i=1
>>> j=2
>>> [i][j]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: list index out of range

Python 列表是一维的，如果您想要一个多维列表，您需要创建一个列表列表或使用一些其他结构，例如 numpy 或 pandas 数组。

一种选择是使用已知值预先分配数组，以便以后可以简单地对其进行索引

@staticmethod
def binary_translating():
    Population.BinaryX = [[None] * 8 for _ in range(10)]
    j = 0
    for i in range(10):
        while Population.CodedX[i] > 1 & j < 8:
            dec = int(Population.CodedX[i]) % 2
            Population.BinaryX[i][j] = dec
            Population.CodedX[i] /= 2
            j += 1
        j = 0

另一种选择是插入到子列表中：

@staticmethod
def binary_translating():
    Population.BinaryX = []
    j = 0
    for i in range(10):
        Population.BinaryX.insert([])
        while Population.CodedX[i] > 1 & j < 8:
            dec = int(Population.CodedX[i]) % 2
            Population.BinaryX[i].insert(j, dec)
            Population.CodedX[i] /= 2
            j += 1
        j = 0

Answer 2

请确保Population.BinaryX 是一个有效实体并且其中至少有10 个元素，因为您正在运行循环10 次。 CodedX 也是如此。

如果其中任何一个都没有至少 10 个元素，你会得到

IndexError: 列表赋值索引超出范围

试试..

class Population:
    CodedX = [0 for i in range(10)]
    BinaryX = [[0 for i in range(10)] for j in range(10)]

这是 tdelaney 提到的预分配。

如果您查看 Application 类中的每个函数，它们会尝试使用 BinaryX 或 CodedX 数组，但如果这些数组中没有任何元素，那么 python 将如何索引它们？

我的意思是在调用decimal_translating() 函数之前，Population.BinrayX 中必须有元素。不能为空数组。

同样，在调用binary_translating() 函数之前，Population.CodedX 中必须有元素。

[编辑 #1] 在您的 cmets 并试图理解您的代码之后。这是我所拥有的：-

class Population(object):
    def __init__(self):
        self.CodedX = [0 for i in range(10)]  # as per your C# code
        self.BinaryX = []
        # debug code to fill CodedX array - remove it
        for i in range(10):
            self.CodedX[i] = int(761)

    def binary_translating(self):
        for i in range(10):
            j = 0
            self.BinaryX.append([0 for k in range(10)])
            while (self.CodedX[i] > 0) and (j < 10):
                dec = int(self.CodedX[i] % 2)
                self.BinaryX[i][j] = dec  # this will append at j
                self.CodedX[i] = int(self.CodedX[i] / 2)
                j += 1
        # debug code to print - remove it
        print(self.BinaryX)
        # debug code to clear CodedX - remove it
        for i in range(10):
            self.CodedX[i] = int(0)

    def decimal_translating(self):
        for i in range(10):
            value = self.BinaryX[i][7] * 128 + self.BinaryX[i][6] * 64 + self.BinaryX[i][5] * 32 + \
                             self.BinaryX[i][4] * 16 + self.BinaryX[i][3] * 8 + self.BinaryX[i][2] * 4 + \
                             self.BinaryX[i][1] * 2 + self.BinaryX[i][0]
            self.CodedX[i] = value
        print(self.CodedX)


pop = Population()

pop.binary_translating()
pop.decimal_translating()

我添加了一些调试代码，以便在 CodedX 中有一些起始值并打印语句供您查看输出。

生成输出：

[[1, 0, 0, 1, 1, 1, 1, 1, 0, 1], [1, 0, 0, 1, 1, 1, 1, 1, 0, 1], [1, 0, 0, 1, 1, 1, 1, 1, 0, 1], [1, 0, 0, 1, 1, 1, 1, 1, 0, 1], [1, 0, 0, 1, 1, 1, 1, 1, 0, 1], [1, 0, 0, 1, 1, 1, 1, 1, 0, 1], [1, 0, 0, 1, 1, 1, 1, 1, 0, 1], [1, 0, 0, 1, 1, 1, 1, 1, 0, 1], [1, 0, 0, 1, 1, 1, 1, 1, 0, 1], [1, 0, 0, 1, 1, 1, 1, 1, 0, 1]]

[249, 249, 249, 249, 249, 249, 249, 249, 249, 249]

[编辑#2]