A couple of changes to the matrix.py module. The ODE solver gave me the idea of how important it was to cut down on copy constructors and destructors. So there were two functions in the Matrix class that would come under that category and will be used almost everywhere.
The function added has been the "resize" function. So if a matrix exists but is now equated to another matrix of another dimension, the object will be modified rather than deleted and built again.
And the zeros function which would initialize self.data in the beginning and then rebuild it now will check whether the object exists. If it doesn't exist, it will initialize and fill it. If the new dimension is different from the existing dimensions, it will resize it.
The __init__ function calls the function zeros with the express arguments of the actual rows and columns of the matrix different from default rows and columns so that a resize takes place.
Finally, the __call__ function has been changed to check if the dimensions are different and resize if so otherwise just equate them.
The addition, subtraction and multiplication operations still need a constructor for the result and the functions will then return that result. But I will try to reduce the need for those in simulations but keep them for error checking as it makes it much easier to type out these operators as regular commands.
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| #! /usr/bin/env python | |
| import sys | |
| class Matrix: | |
| """ For defining arrays of any given size. | |
| Contains overloaded operators for print, add, subtract and multiply. Does not contain = assignment operator! Use a(b) instead of a=b. | |
| Last updated - Dec 30, 2012 """ | |
| def resize(self, rows, columns=1): | |
| """ Changes the dimension of an existing matrix by add/deleting difference of rows and columns.""" | |
| if (rows<self.rows): | |
| for c1 in range(self.rows-1,rows-1,-1): | |
| del self.data[c1] | |
| self.rows=rows | |
| if (columns<self.columns): | |
| for c1 in range(self.rows): | |
| for c2 in range(self.columns-1, columns-1, -1): | |
| del self.data[c1][c2] | |
| for c1 in range(self.rows, rows): | |
| row_vector=[] | |
| for c2 in range(columns): | |
| row_vector.append(0) | |
| self.data.append(row_vector) | |
| else: | |
| for c1 in range(self.rows): | |
| for c2 in range(self.columns, columns): | |
| self.data[c1].append(0) | |
| for c1 in range(self.rows, rows): | |
| row_vector=[] | |
| for c2 in range(columns): | |
| row_vector.append(0) | |
| self.data.append(row_vector) | |
| self.rows=rows | |
| self.columns=columns | |
| return | |
| def zeros(self, rows, columns=1): | |
| """ Creates a zero matrix | |
| Dimensions have to be passed as <Matrix>.zeros(rows, columns). | |
| This function also creates the actual array. So every method of the class/object should call this first before using the array.""" | |
| try: | |
| if self.data: pass | |
| except: | |
| self.data=[] | |
| for count1 in range(self.rows): | |
| row_vector=[] | |
| for count2 in range(self.columns): | |
| row_vector.append(0.0) | |
| self.data.append(row_vector) | |
| if not (self.rows==rows and self.columns==columns): | |
| self.resize(rows, columns) | |
| # self.data=[] Removed on Dec. 30 due to resize() function addition to class. | |
| for count1 in range(self.rows): | |
| #row_vector=[] Removed on Dec. 30 due to resize() function addition to class. | |
| for count2 in range(self.columns): | |
| #row_vector.append(0.0) Removed on Dec. 30 due to resize() function addition to class. | |
| self.data[count1][count2]=0.0 | |
| #self.data.append(row_vector) Removed on Dec. 30 due to resize() function addition to class. | |
| return | |
| def __init__(self, rows=1, columns=1): | |
| """Creates an object with a zero array of size rowsXcolumns. | |
| If only one dimension is specified specified, a column vector is assumed. If no dimensions are specified, an null matrix is created.""" | |
| self.rows=1 | |
| self.columns=1 | |
| self.zeros(rows, columns) | |
| def __call__(self, matrix1): | |
| """ Replaces the assignment operator =. Use as c(b) instead of c=b. | |
| The = will only result in a reference to the object and not an actual copy. This method ensures it. """ | |
| #self.rows=matrix1.rows Removed on Dec. 30 due to resize() function addition to class. | |
| #self.columns=matrix1.columns Removed on Dec. 30 due to resize() function addition to class. | |
| if not (self.rows==matrix1.rows and self.columns==matrix1.columns): | |
| self.resize(matrix1.rows, matrix1.columns) | |
| for count1 in range(self.rows): | |
| for count2 in range(self.columns): | |
| self.data[count1][count2]=matrix1.data[count1][count2] | |
| def identity(self, rows): | |
| """ Generates an identity matrix of rowsXrows. """ | |
| self.rows=rows | |
| self.columns=rows | |
| self.zeros(self.rows, self.columns) | |
| for count in range(self.rows): | |
| self.data[count][count]=1.0 | |
| def display(self): | |
| """ Explicit method for displaying an array. """ | |
| for count1 in range(self.rows): | |
| for count2 in range(self.columns): | |
| print self.data[count1][count2], | |
| print "\t", | |
| print "\n", | |
| def __repr__(self): | |
| """ Displays an array when print <Matrix> is used. """ | |
| for count1 in range(self.rows): | |
| for count2 in range(self.columns): | |
| print self.data[count1][count2], | |
| print "\t", | |
| print "\n", | |
| return " " | |
| def __add__(self, matrix1): | |
| """ Left addition of two matrices. """ | |
| add_result=Matrix(self.rows, self.columns) | |
| try: | |
| if matrix1.rows: pass | |
| except AttributeError: | |
| print "*"*40 | |
| print "Can't add a float or integer to a matrix directly." | |
| print "*"*40 | |
| sys.exit("Logic Error") | |
| else: | |
| if not (self.rows==matrix1.rows and self.columns==matrix1.columns): | |
| print "Matrices not compatible for summation." | |
| sys.exit("Logic Error") | |
| else: | |
| for count1 in range(self.rows): | |
| for count2 in range(self.columns): | |
| add_result.data[count1][count2]=self.data[count1][count2]+matrix1.data[count1][count2] | |
| return add_result | |
| def __radd__(self, matrix1): | |
| """ Right addition of two matrices. """ | |
| add_result=Matrix(self.rows, self.columns) | |
| try: | |
| if matrix1.rows: pass | |
| except AttributeError: | |
| print "*"*40 | |
| print "Can't add a float or integer to a matrix directly." | |
| print "*"*40 | |
| sys.exit("Logic Error") | |
| else: | |
| if not (self.rows==matrix1.rows and self.columns==matrix1.columns): | |
| print "Matrices not compatible for summation." | |
| else: | |
| for count1 in range(self.rows): | |
| for count2 in range(self.columns): | |
| add_result.data[count1][count2]=self.data[count1][count2]+matrix1.data[count1][count2] | |
| return add_result | |
| def __sub__(self, matrix1): | |
| """ Left subtraction of two matrices. """ | |
| sub_result=Matrix(self.rows, self.columns) | |
| try: | |
| if matrix1.rows: pass | |
| except AttributeError: | |
| print "*"*40 | |
| print "Can't subtract a float or integer to a matrix directly." | |
| print "*"*40 | |
| sys.exit("Logic Error") | |
| else: | |
| if not (self.rows==matrix1.rows and self.columns==matrix1.columns): | |
| print "Matrices not compatible for subtraction." | |
| sys.exit("Logic Error") | |
| else: | |
| for count1 in range(self.rows): | |
| for count2 in range(self.columns): | |
| sub_result.data[count1][count2]=self.data[count1][count2]-matrix1.data[count1][count2] | |
| return sub_result | |
| def __rsub__(self, matrix1): | |
| """ Right subtraction of two mnatrices. """ | |
| sub_result=Matrix(self.rows, self.columns) | |
| try: | |
| if matrix1.rows: pass | |
| except AttributeError: | |
| print "*"*40 | |
| print "Can't subtract a float or integer to a matrix directly." | |
| print "*"*40 | |
| sys.exit("Logic Error") | |
| else: | |
| if not (self.rows==matrix1.rows and self.columns==matrix1.columns): | |
| print "Matrices not compatible for subtraction." | |
| sys.exit("Logic Error") | |
| else: | |
| for count1 in range(self.rows): | |
| for count2 in range(self.columns): | |
| sub_result.data[count1][count2]=matrix1.data[count1][count2]-self.data[count1][count2] | |
| return sub_result | |
| def __mul__(self, matrix1): | |
| """ Left multiplication of two matrices. | |
| The multiplication is NOT done elementwise but in the conventional mathematical sense. """ | |
| try: | |
| if matrix1.rows: pass | |
| except AttributeError: | |
| mul_result=Matrix(self.rows, self.columns) | |
| for count1 in range(self.rows): | |
| for count2 in range(self.columns): | |
| mul_result.data[count1][count2]=self.data[count1][count2]*matrix1 | |
| else: | |
| mul_result=Matrix() | |
| if not (self.columns==matrix1.rows): | |
| print "Matrices not compatible for multiplication." | |
| else: | |
| mul_result.zeros(self.rows, matrix1.columns) | |
| for count1 in range(self.rows): | |
| for count2 in range(matrix1.columns): | |
| for count3 in range(self.columns): | |
| mul_result.data[count1][count2]+=self.data[count1][count3]*matrix1.data[count3][count2] | |
| return mul_result | |
| def __rmul__(self, matrix1): | |
| """ Right multiplication of two matrices. | |
| The multiplication is NOT done elementwise but in the conventional mathematical sense. """ | |
| try: | |
| if matrix1.rows: pass | |
| except AttributeError: | |
| mul_result=Matrix(self.rows, self.columns) | |
| for count1 in range(self.rows): | |
| for count2 in range(self.columns): | |
| mul_result.data[count1][count2]=self.data[count1][count2]*matrix1 | |
| else: | |
| mul_result=Matrix() | |
| if not (self.rows==matrix1.columns): | |
| print "Matrices not compatible for multiplication." | |
| else: | |
| mul_result.zeros(matrix1.rows, self.columns) | |
| for count1 in range(matrix1.rows): | |
| for count2 in range(self.columns): | |
| for count3 in range(self.rows): | |
| mul_result.data[count1][count2]+=self.data[count1][count3]*matrix1.data[count3][count2] | |
| return mul_result | |
| def transpose(self): | |
| """ Returns a matrix that is transpose of the calling object array. A new object is returned. Original object is untouched. """ | |
| trans_result=Matrix(self.columns, self.rows) | |
| for count1 in range(self.rows): | |
| for count2 in range(self.columns): | |
| trans_result.data[count2][count1]=self.data[count1][count2] | |
| return trans_result |
The function added has been the "resize" function. So if a matrix exists but is now equated to another matrix of another dimension, the object will be modified rather than deleted and built again.
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| def resize(self, rows, columns=1): | |
| """ Changes the dimension of an existing matrix by add/deleting difference of rows and columns.""" | |
| if (rows<self.rows): | |
| for c1 in range(self.rows-1,rows-1,-1): | |
| del self.data[c1] | |
| self.rows=rows | |
| if (columns<self.columns): | |
| for c1 in range(self.rows): | |
| for c2 in range(self.columns-1, columns-1, -1): | |
| del self.data[c1][c2] | |
| for c1 in range(self.rows, rows): | |
| row_vector=[] | |
| for c2 in range(columns): | |
| row_vector.append(0) | |
| self.data.append(row_vector) | |
| else: | |
| for c1 in range(self.rows): | |
| for c2 in range(self.columns, columns): | |
| self.data[c1].append(0) | |
| for c1 in range(self.rows, rows): | |
| row_vector=[] | |
| for c2 in range(columns): | |
| row_vector.append(0) | |
| self.data.append(row_vector) | |
| self.rows=rows | |
| self.columns=columns | |
| return |
And the zeros function which would initialize self.data in the beginning and then rebuild it now will check whether the object exists. If it doesn't exist, it will initialize and fill it. If the new dimension is different from the existing dimensions, it will resize it.
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| def zeros(self, rows, columns=1): | |
| """ Creates a zero matrix | |
| Dimensions have to be passed as <Matrix>.zeros(rows, columns). | |
| This function also creates the actual array. So every method of the class/object should call this first before using the array.""" | |
| try: | |
| if self.data: pass | |
| except: | |
| self.data=[] | |
| for count1 in range(self.rows): | |
| row_vector=[] | |
| for count2 in range(self.columns): | |
| row_vector.append(0.0) | |
| self.data.append(row_vector) | |
| if not (self.rows==rows and self.columns==columns): | |
| self.resize(rows, columns) | |
| # self.data=[] Removed on Dec. 30 due to resize() function addition to class. | |
| for count1 in range(self.rows): | |
| #row_vector=[] Removed on Dec. 30 due to resize() function addition to class. | |
| for count2 in range(self.columns): | |
| #row_vector.append(0.0) Removed on Dec. 30 due to resize() function addition to class. | |
| self.data[count1][count2]=0.0 | |
| #self.data.append(row_vector) Removed on Dec. 30 due to resize() function addition to class. | |
| return |
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| def __init__(self, rows=1, columns=1): | |
| """Creates an object with a zero array of size rowsXcolumns. | |
| If only one dimension is specified specified, a column vector is assumed. If no dimensions are specified, an null matrix is created.""" | |
| self.rows=1 | |
| self.columns=1 | |
| self.zeros(rows, columns) |
Finally, the __call__ function has been changed to check if the dimensions are different and resize if so otherwise just equate them.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
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| def __call__(self, matrix1): | |
| """ Replaces the assignment operator =. Use as c(b) instead of c=b. | |
| The = will only result in a reference to the object and not an actual copy. This method ensures it. """ | |
| #self.rows=matrix1.rows Removed on Dec. 30 due to resize() function addition to class. | |
| #self.columns=matrix1.columns Removed on Dec. 30 due to resize() function addition to class. | |
| if not (self.rows==matrix1.rows and self.columns==matrix1.columns): | |
| self.resize(matrix1.rows, matrix1.columns) | |
| for count1 in range(self.rows): | |
| for count2 in range(self.columns): | |
| self.data[count1][count2]=matrix1.data[count1][count2] | |
The addition, subtraction and multiplication operations still need a constructor for the result and the functions will then return that result. But I will try to reduce the need for those in simulations but keep them for error checking as it makes it much easier to type out these operators as regular commands.
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