在python中从2D数组类创建一个对象


Create an object from 2D array class in python

目前我有一个使用python的数据结构课程。在书中，它们包含了两个不同的类来实现一维数组结构和二维数组。

一维数组：

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import ctypes

class Array:

    def __init__(self, size):
        assert size > 0,"Array size must be > 0"
        self._size = size
        PyArrayType = ctypes.py_object * size
        self._elements = PyArrayType()
        self.clear(None)

    def len(self):
        return self._size

    def getitem(self, index):
        assert index >= 0 and index < self.len(),"Array subscript out of range"
        return self._elements[index]

    def setitem(self, index, value):
        assert 0 <= index < self.len(),"Array subscript out of range"
        self._elements[index] = value

    def clear(self, value):
        for i in range(self.len()):
            self._elements[i] = value

    def iter(self):
        return ArrayIterator(self._elements )

class ArrayIterator:
    def __init__(self, theArray):
        self._arrayRef = theArray
        self._curNdx = 0

    def __iter__(self):
        return self

    def __next__(self):
        if self._curNdx < len(self._arrayRef):
            entry = self._arrayRef[self._curNdx]
            self._curNdx += 1
            return entry
        else:
            raise StopIteration

class Array2D :

    def __init__( self, numRows, numCols ):
        self._theRows = Array( numRows )
        for i in range( numRows ) :
            self._theRows[i] = Array( numCols )

    def numRows( self ):
        return len( self._theRows )

    def numCols( self ):
        return len( self._theRows[0] )

    def clear( self, value ):
        for row in range( self.numRows() ):
            row.clear( value )

    def __getitem__( self, ndxTuple ):
        assert len(ndxTuple) == 2,"Invalid number of array subscripts."
        row = ndxTuple[0]
        col = ndxTuple[1]
        assert row >= 0 and row < self.numRows() \
            and col >= 0 and col < self.numCols(), \
              "Array subscript out of range."
        the1dArray = self._theRows[row]

        return the1dArray[col]

    def __setitem__( self, ndxTuple, value ):
        assert len(ndxTuple) == 2,"Invalid number of array subscripts."
        row = ndxTuple[0]
        col = ndxTuple[1]
        assert row >= 0 and row < self.numRows() \
            and col >= 0 and col < self.numCols(), \
               "Array subscript out of range."
       the1dArray = self._theRows[row]
       the1dArray[col] = value

我使用以下代码来理解它的工作原理：

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arr = Array(5)
arrLen = arr.len()
arr.clear(0)
for i in range (arrLen):
   print arr.getitem(i)

print"The length of the array =",arrLen

print"Enter 5 numbers"
for i in range (arrLen):
#n = raw_input("num =")
arr.setitem(i,i)

for i in range (arrLen):
print arr.getitem(i)
print"values are", arr.iter()

但是，我不知道如何调用二维数组来理解它是如何工作的。

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ArrMulti = Array2D(3, 4)

我得到了以下错误：

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File"MultiArrayADT.py", line 46, in __init__
   self._theRows[i] = Array( numCols )
AttributeError: Array instance has no attribute '__setitem__'

所以请有人告诉我如何创建一个二维数组对象。

在您的Array类中，您应该在实现setitem()的同时重写方法__setitem__()。所以尝试更改方法的名称。那应该管用。同getitem()。