每日一貼,明天的內容關鍵字為二維、呼叫-
明天就到了二維的了.python中認默是沒有帶二維的據數結構的.二維的據數結構可以通過一維的據數成組.碼代如下
class注意下呼叫情勢,這裡的是實現了 __getitem__ ,__setitem__,這裡是這樣呼叫的 如a = array2d(2,3) a[1,2] = 5array2d:
def__init__
(self,numrows,numcols):
self._therows =array(numrows)
for i in
range(numrows):
self._therows[i] =array(numcols)
defnumrows(self):
return
len(self._therows)
defnumcols(self):
return
len(self._therows[0])
defclear(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
and col >= 0 and col
"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
and col >= 0 and col
"array subscript out of range
"the1darray =self._therows[row]
the1darray[col] = value
當然也可以像c/c++那樣,改寫下__getitem__
def這時呼叫就是這模樣 val = a[1][2] 和a[1,2] = val,連__setitem__都不要寫了.相當於2次函式呼叫.__getitem__
(self,row):
return self._thwrows[row]
說到二維組數天然想到矩陣(matrix).
當然實際用使時是直接用使numpy庫拉.
實現碼代如下,其實只是在array2d上加了幾個簡略的作操而已.
from array import測試也很簡略.array2d
class
matrix:
def__init__
(self,numrows,numcols):
self._thegrid =array2d(numrows,numcols)
self._thegrid.clear(0)
defnumrows(self):
return
self._thegrid.numrows()
defnumcols(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
defscaleby(self,scalar):
for r in
range(self.numrows()):
for c in
range(self.numcols()):
self[r,c] *=scalar
deftranpose(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
嗯,好了睡覺...
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