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https://github.com/TheAlgorithms/Python.git
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Update lib.py
replaced size() with __len__ built-in changed self.__components = components to self.__components = list(components) replacing for loops with list comprehension allowing -ve indexing in component() and changeComponent()
This commit is contained in:
Ashwek Swamy
GitHub
parent
70a6d98e0f
commit
63b2c4efe0
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@ -36,7 +36,7 @@ class Vector(object):
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set(components : list) : changes the vector components.
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__str__() : toString method
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component(i : int): gets the i-th component (start by 0)
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size() : gets the size of the vector (number of components)
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__len__() : gets the size of the vector (number of components)
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euclidLength() : returns the eulidean length of the vector.
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operator + : vector addition
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operator - : vector subtraction
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@ -50,7 +50,7 @@ class Vector(object):
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input: components or nothing
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simple constructor for init the vector
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"""
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self.__components = components
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self.__components = list(components)
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def set(self,components):
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"""
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input: new components
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@ -58,33 +58,24 @@ class Vector(object):
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replace the components with newer one.
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"""
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if len(components) > 0:
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self.__components = components
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self.__components = list(components)
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else:
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raise Exception("please give any vector")
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def __str__(self):
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"""
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returns a string representation of the vector
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"""
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ans = "("
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length = len(self.__components)
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for i in range(length):
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if i != length-1:
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ans += str(self.__components[i]) + ","
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else:
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ans += str(self.__components[i]) + ")"
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if len(ans) == 1:
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ans += ")"
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return ans
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return "(" + ",".join(map(str, self.__components)) + ")"
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def component(self,i):
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"""
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input: index (start at 0)
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output: the i-th component of the vector.
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"""
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if i < len(self.__components) and i >= 0:
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if type(i) is int and -len(self.__components) <= i < len(self.__components) :
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return self.__components[i]
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else:
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raise Exception("index out of range")
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def size(self):
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def __len__(self):
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"""
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returns the size of the vector
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"""
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@ -103,9 +94,9 @@ class Vector(object):
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assumes: other vector has the same size
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returns a new vector that represents the sum.
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"""
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size = self.size()
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size = len(self)
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result = []
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if size == other.size():
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if size == len(other):
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for i in range(size):
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result.append(self.__components[i] + other.component(i))
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else:
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@ -117,9 +108,9 @@ class Vector(object):
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assumes: other vector has the same size
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returns a new vector that represents the differenz.
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"""
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size = self.size()
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size = len(self)
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result = []
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if size == other.size():
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if size == len(other):
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for i in range(size):
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result.append(self.__components[i] - other.component(i))
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else: # error case
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@ -134,8 +125,8 @@ class Vector(object):
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if isinstance(other,float) or isinstance(other,int):
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for c in self.__components:
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ans.append(c*other)
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elif (isinstance(other,Vector) and (self.size() == other.size())):
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size = self.size()
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elif (isinstance(other,Vector) and (len(self) == len(other))):
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size = len(self)
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summe = 0
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for i in range(size):
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summe += self.__components[i] * other.component(i)
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@ -147,8 +138,7 @@ class Vector(object):
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"""
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copies this vector and returns it.
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"""
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components = [x for x in self.__components]
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return Vector(components)
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return Vector(self.__components)
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def changeComponent(self,pos,value):
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"""
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input: an index (pos) and a value
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@ -156,7 +146,7 @@ class Vector(object):
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'value'
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"""
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#precondition
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assert (pos >= 0 and pos < len(self.__components))
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assert (-len(self.__components) <= pos < len(self.__components))
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self.__components[pos] = value
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def zeroVector(dimension):
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@ -165,10 +155,7 @@ def zeroVector(dimension):
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"""
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#precondition
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assert(isinstance(dimension,int))
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ans = []
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for i in range(dimension):
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ans.append(0)
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return Vector(ans)
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return Vector([0]*dimension)
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def unitBasisVector(dimension,pos):
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@ -178,12 +165,8 @@ def unitBasisVector(dimension,pos):
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"""
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#precondition
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assert(isinstance(dimension,int) and (isinstance(pos,int)))
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ans = []
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for i in range(dimension):
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if i != pos:
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ans.append(0)
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else:
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ans.append(1)
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ans = [0]*dimension
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ans[pos] = 1
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return Vector(ans)
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@ -206,11 +189,9 @@ def randomVector(N,a,b):
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output: returns a random vector of size N, with
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random integer components between 'a' and 'b'.
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"""
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ans = zeroVector(N)
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random.seed(None)
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for i in range(N):
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ans.changeComponent(i,random.randint(a,b))
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return ans
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ans = [random.randint(a,b) for i in range(N)]
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return Vector(ans)
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class Matrix(object):
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@ -220,7 +201,7 @@ class Matrix(object):
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Overview about the methods:
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__str__() : returns a string representation
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__str__() : returns a string representation
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operator * : implements the matrix vector multiplication
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implements the matrix-scalar multiplication.
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changeComponent(x,y,value) : changes the specified component.
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@ -284,7 +265,7 @@ class Matrix(object):
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implements the matrix-scalar multiplication
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"""
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if isinstance(other, Vector): # vector-matrix
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if (other.size() == self.__width):
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if (len(other) == self.__width):
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ans = zeroVector(self.__height)
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for i in range(self.__height):
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summe = 0
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@ -294,15 +275,9 @@ class Matrix(object):
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summe = 0
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return ans
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else:
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raise Exception("vector must have the same size as the "
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+ "number of columns of the matrix!")
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raise Exception("vector must have the same size as the " + "number of columns of the matrix!")
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elif isinstance(other,int) or isinstance(other,float): # matrix-scalar
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matrix = []
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for i in range(self.__height):
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row = []
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for j in range(self.__width):
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row.append(self.__matrix[i][j] * other)
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matrix.append(row)
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matrix = [[self.__matrix[i][j] * other for j in range(self.__width)] for i in range(self.__height)]
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return Matrix(matrix,self.__width,self.__height)
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def __add__(self,other):
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"""
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@ -338,12 +313,7 @@ def squareZeroMatrix(N):
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"""
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returns a square zero-matrix of dimension NxN
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"""
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ans = []
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for i in range(N):
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row = []
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for j in range(N):
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row.append(0)
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ans.append(row)
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ans = [[0]*N for i in range(N)]
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return Matrix(ans,N,N)
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@ -352,13 +322,8 @@ def randomMatrix(W,H,a,b):
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returns a random matrix WxH with integer components
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between 'a' and 'b'
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"""
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matrix = []
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random.seed(None)
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for i in range(H):
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row = []
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for j in range(W):
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row.append(random.randint(a,b))
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matrix.append(row)
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matrix = [[random.randint(a,b) for j in range(W)] for i in range(H)]
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return Matrix(matrix,W,H)
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