我必须实现一些将矩阵设置为单位矩阵的方法。听起来很简单,但我不允许使用NumPy。
class Matrix4():
def __init__(self, row1=None, row2=None, row3=None, row4=None):
"""Constructor for Matrix4
DO NOT MODIFY THIS METHOD"""
if row1 is None: row1 = Vec4()
if row2 is None: row2 = Vec4()
if row3 is None: row3 = Vec4()
if row4 is None: row4 = Vec4()
self.m_values = [row1,row2,row3,row4]
def __str__(self):
"""Returns a string representation of the matrix
DO NOT MODIFY THIS METHOD"""
toReturn = ''
if self is None: return '0.00 0.00 0.00 0.00\n0.00 0.00 0.00 0.00\n0.00 0.00 0.00 0.00\n0.00 0.00 0.00 0.00'
for r in range(0,4):
for c in range(0,4):
toReturn += "%.2f" % self.m_values[r].values[c]
if c != 3:
toReturn += ' '
toReturn += '\n'
return toReturn
def setIdentity(self):
"""Sets the current Matrix to an identity matrix
self is an identity matrix after calling this method"""
row1 = Vec4(1,0,0,0)
row2 = Vec4(0,1,0,0)
row3 = Vec4(0,0,1,0)
row4 = Vec4(0,0,0,1)
setIdentity.Matrix4()
return Matrix4(row1, row2, row3, row4)
如您所见,我们有一个Matrix4()类,到目前为止,我已经实现了该方法。如果我尝试打印出身份矩阵,它将失败。 命令
print(Matrix4())
打印出零矩阵。执行以下命令
print(setIdentity.Matrix4())
告诉我未实现setIdentity。我的代码有什么问题?
我愿意接受您的建议。
谢谢!
答案 0 :(得分:1)
您确实应该部分执行此操作,因为您似乎缺少一些概念。
m = Matrix4()
现在您有了一个全零的矩阵。接下来,您要将其设为单位矩阵。
m.setIdentity()
您当前的实现方式受到了很多破坏。
def setIdentity(self):
"""Sets the current Matrix to an identity matrix
self is an identity matrix after calling this method"""
row1 = Vec4(1,0,0,0)
row2 = Vec4(0,1,0,0)
row3 = Vec4(0,0,1,0)
row4 = Vec4(0,0,0,1)
#setIdentity.Matrix4()~
#return Matrix4(row1, row2, row3, row4)
self.m_values = [row1, row2, row3, row4]
这解决了setIdentity
未被定义的两个问题,并且不返回新矩阵,而是修改了现有矩阵。
我将在下面修复您的答案代码。
class Matrix4():
def __init__(self, row1=None, row2=None, row3=None, row4=None):
"""Constructor for Matrix4
DO NOT MODIFY THIS METHOD"""
if row1 is None: row1 = Vec4()
if row2 is None: row2 = Vec4()
if row3 is None: row3 = Vec4()
if row4 is None: row4 = Vec4()
self.m_values = [row1,row2,row3,row4]
def __str__(self):
"""Returns a string representation of the matrix
DO NOT MODIFY THIS METHOD"""
toReturn = ''
if self is None: return '0.00 0.00 0.00 0.00\n0.00 0.00 0.00 0.00\n0.00 0.00 0.00 0.00\n0.00 0.00 0.00 0.00'
for r in range(0,4):
for c in range(0,4):
toReturn += "%.2f" % self.m_values[r].values[c]
if c != 3:
toReturn += ' '
toReturn += '\n'
return toReturn
def setIdentity(self):
"""Sets the current Matrix to an identity matrix
self is an identity matrix after calling this method"""
#Dont do this either, it is unescessary!
#m = Matrix4()
row1 = Vec4(1,0,0,0)
row2 = Vec4(0,1,0,0)
row3 = Vec4(0,0,1,0)
row4 = Vec4(0,0,0,1)
self.m_values = [row1, row2, row3, row4]
#No, do do this! this is causing the recursion!
#m.setIdentity()
#Stop returning a new matrix!
#return Matrix4(row1, row2, row3, row4)
m = Matrix4()
m.setIdentity()
print(m)
用于创建矩阵并将其设置为标识的代码应该在您的类的外面。此时您正在使用该类。我在删除的行上方添加了注释。我只更改了setIdentity方法。
答案 1 :(得分:0)
如果要从 Matrix4 类执行函数 setIdentity ,则必须以以下方式编写:
(class instance).function()
因此,在您的情况下:
print(Matrix4().setIdentity())
关于您的代码:
print(Matrix4())
它不起作用,因为它调用构造函数( init )创建Matrix4的默认实例。如果要使用其他矩阵作为默认值,则必须修改init函数。
答案 2 :(得分:0)