二维、调用-Python和数据结构学习 -by小雨

htbzwd

　　每日一贴,明天的内容关键字为二维、调用-
　　明天就到了二维的了.Python中认默是没有带二维的据数结构的.二维的据数结构可以通过一维的据数成组.码代如下

class Array2D:
def __init__(self,numRows,numCols):
self._theRows = Array(numRows)
for i in range(numRows):
self._theRows = Array(numCols)
def numRows(self):
return len(self._theRows)
def numCols(self):
return len(self._theRows[0])
def clear(self,value):
for r in range(self.numRows()):
self._theRows[r].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   

　　注意下调用情势,这里的是实现了 __getitem__ ,__setitem__,这里是这样调用的 如a = Array2D(2,3) a[1,2] = 5
　　当然也可以像c/c++那样,改写下__getitem__

def __getitem__(self,row):
return self._thwRows[row]

　　这时调用就是这模样 val = a[1][2] 和a[1,2] = val,连__setitem__都不要写了.相当于2次函数调用.
　　说到二维组数天然想到矩阵(Matrix).
　　当然实际用使时是直接用使numpy庫拉.
　　实现码代如下,其实只是在Array2D上加了几个简略的作操而已.

from array import Array2D
class Matrix:
def __init__(self,numRows,numCols):
self._theGrid = Array2D(numRows,numCols)
self._theGrid.clear(0)
def numRows(self):
return self._theGrid.numRows()
def numCols(self):
return self._theGrid.numCols()
def __getitem__(self,ndxTuple):
return self._theGrid[ndxTuple[0],ndxTuple[1]]
def __setitem__(self,ndxTuple,scalar):
self._theGrid[ndxTuple[0],ndxTuple[1]] = scalar
def scaleBy(self,scalar):
for r in range(self.numRows()):
for c in range(self.numCols()):
self[r,c] *= scalar
def tranpose(self):
newMatrix = Matrix(self.numCols(),self.numRows())
for r in range(self.numRows()):
for c in range(self.numCols()):
newMatrix[c,r] = self._theGrid[r,c]
return newMatrix
def __add__(self,rhsMatrix):
assert rhsMatrix.numRows() == self.numRows() and \
rhsMatrix.numCols() == self.numCols(),\
"Matrix sizes not compatible for the add operation"
newMatrix = Matrix(self.numRows(),self.numCols())
for r in range(self.numRows()):
for c in range(self.numCols()):
newMatrix[r,c] = self[r,c] + rhsMatrix[r,c]
return newMatrix
def __sub__(self,rhsMatrix):
assert rhsMatrix.numRows() == self.numRows() and \
rhsMatrix.numCols() == self.numCols(),\
"Matrix sizes not compatible for the add operation"
newMatrix = Matrix(self.numRows(),self.numCols())
for r in range(self.numRows()):
for c in range(self.numCols()):
newMatrix[r,c] = self[r,c] - rhsMatrix[r,c]
return newMatrix
def __mul__(self,rhsMatrix):
assert rhsMatrix.numRows() == self.numCols() ,\
"Matrix sizes not compatible for the add operation"
newR = self.numRows()
newC = rhsMatrix.numCols()
newK = self.numCols()
newMatrix = Matrix(newR,newC)
for r in range(newR):
for c in range(newC):
temp = 0
for k in range(newK):
temp += self._theGrid[r,k]*rhsMatrix[k,c]
newMatrix[r,c] = temp
return newMatrix

　　测试也很简略.

　　嗯,好了睡觉...
　　文章结束给大家分享下程序员的一些笑话语录： 一位程序员去海边游泳，由于水性不佳，游不回岸了，于是他挥着手臂，大声求.救：“F1，F1！”