Basic Vectors in IronPython QuickStart Sample

Illustrates the basic use of the Vector class for working with vectors in IronPython.

This sample is also available in: C#, Visual Basic, F#.

Overview

This QuickStart sample demonstrates the fundamental operations and concepts of working with vectors in Numerics.NET.

The sample illustrates the various ways to create and manipulate vectors using the Vector class from the Numerics.NET.LinearAlgebra namespace. It covers:

Different methods for constructing vectors including from arrays and individual elements
Working with vector properties like Length
Accessing and modifying vector elements using indexers
Understanding vector mutability options
Performing vector operations like copying and cloning
Managing shared storage between vectors
Setting vector values using methods like SetValue and SetToZero

Through detailed examples and output, the sample shows how to effectively use vectors as the building blocks for linear algebra operations in Numerics.NET.

The code

import numerics

from System import Array

# The Vector class resides in the Extreme.Mathematics.LinearAlgebra
# namespace.
from Extreme.Mathematics import *

# Illustrates the use of the Vector class in the 
# Extreme.Mathematics.LinearAlgebra namespace of Extreme Numerics.NET.

#
# Constructing vectors
#

# Option #1: specify the number of elements. All
# components are set to 0.
v1 = Vector.Create[float](5)
# Option #2: specify the components:
v2 = Vector.Create(1.0, 2.0, 3.0, 4.0, 5.0)
# Option #3: specify the components as a double array.
# By default, the components are copied to a storage
# area internal to the Vector.
components = Array[float]([ 1, 2, 3, 4, 5 ])
v3 = Vector.Create(components)
### In Python, you can also use a list:
### v3 = Vector([ 1, 2, 3, 4, 5 ])
# Option #4: same as above, but specify whether
# to copy the components, or use the array as 
# internal storage.
v4 = Vector.Create(components, False)
# Changing a value in the original vector changes
# the resulting vector.
print 'v4 = {0:.4f}'.format(v4)
components[3] = 1
print 'v4 = {0:.4f}'.format(v4)
# Option #5: same as #4, but specify the length of
# the Vector. The remaining elements in the component
# array will be ignored.
v5 = Vector.Create(4, components, False)

### In IronPython, you can also create vectors from a list:
##v6 = Vector([1,2,3,4,5])

#
# Vector properties
#
			
# The Length property gives the number of components
# of a Vector:
print 'v1.Length =', v1.Length
# The ToArray method returns a double array
# that contains the components of the vector.
# This is always a copy:
components = v2.ToArray()
print 'Effect of shared storage:'
print 'v2[2] =', v2[2]
components[2] = 1
print 'v2[2] =', v2[2]

#
# Accessing vector elements
#

# The Vector class defines an indexer property that
# takes a zero-based index.
print 'Assigning with private storage:'
print 'v1[2] =', v1[2]
# You can assign to this property:
v1[2] = 7
print 'v1[2] =', v1[2]
# The vectors v4 and v5 had the copy parameter in the
# constructor set to false. As a result, they share 
# their component storage. Changing one vector also 
# changes the other:
print 'Assigning with shared storage:'
print 'v4[1] =', v4[1]
v4[1] = 7
print 'v4[1] =', v4[1]

# The SetValue method sets all components of a vector
# to the same value:
v1.SetValue(1)
print 'v1 = {0:.4f}'.format(v1)
# The SetToZero method sets all components to 0:
v1.SetToZero()
print 'v1 = {0:.4f}'.format(v1)

#
# Copying and cloning vectors
#

# A shallow copy of a vector constructs a vector
# that shares the component storage with the original.
# This is done using the ShallowCopy method:
print 'Shallow copy vs. clone:'
v7 = v2.ShallowCopy()
# The clone method creates a full copy.
v8 = v2.Clone()
# When we change v2, v7 changes, but v8 is left
# unchanged.
print 'v2[1] =', v2[1]
v2[1] = -2
print 'v7[1] =', v7[1]
print 'v8[1] =', v8[1]
# We can give a vector its own component storage
# by calling the CloneData method:
print 'CloneData:'
v7.CloneData()
# Now, changing the original v2 no longer changes v7:
v2[1] = 4
print 'v7[1] =', v7[1]
# The CopyTo method copies the components of a Vector
# to a variety of destinations. It may be a Vector:
print 'CopyTo:'
v5.CopyTo(v1)
print 'v5 = {0:.4f}'.format(v5)
print 'v1 = {0:.4f}'.format(v1)
# You can specify an index where to start copying
# in the destination vector:
v5.CopyTo(v1, 1)
print 'v1 = {0:.4f}'.format(v1)
# Or you can copy to a double array:
v5.CopyTo(components)