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| 1 | +Attribute VB_Name = "Module1" |
| 2 | +'############################################################################################## |
| 3 | +'# John Wiley & Sons, Inc. # |
| 4 | +'# # |
| 5 | +'# Book: Markov Chains: From Theory To Implementation And Experimentation # |
| 6 | +'# Author: Dr. Paul Gagniuc # |
| 7 | +'# Data: 01/09/2016 # |
| 8 | +'# # |
| 9 | +'# Description: # |
| 10 | +'# Supporting algorithm 10. Predictions based on sequences produced by n-state # |
| 11 | +'# Markov machines. This example also uses a DNA sequence as a model. However, # |
| 12 | +'# the algorithm allows for an unlimited number of letters (observations). # |
| 13 | +'# Previously, the vector – matrix multiplication cycle was declared manually # |
| 14 | +'# with a range of expressions. Here, the multiplication cycle is made # |
| 15 | +'# iteratively. For a prediction on more than 4 states, the matrix elements # |
| 16 | +'# and the number of vector components can be increased to cover a new # |
| 17 | +'# prediction requirement. Note that “ExtractProb” function is not shown. # |
| 18 | +'# However, when the above algorithm is used the “ExtractProb” function # |
| 19 | +'# must be present. # |
| 20 | +'############################################################################################## |
| 21 | + |
| 22 | +Dim M(1 To 4, 1 To 4) As String |
| 23 | + |
| 24 | +Private Sub main() |
| 25 | + |
| 26 | +Dim v(0 To 3, 0 To 1) As Variant |
| 27 | + |
| 28 | +Call ExtractProb("TACTTCGATTTAAGCGCGGCGGCCTATATTA") |
| 29 | + |
| 30 | +chain = 5 |
| 31 | + |
| 32 | +v(0, 0) = 1 |
| 33 | +v(1, 0) = 0 |
| 34 | +v(2, 0) = 0 |
| 35 | +v(3, 0) = 0 |
| 36 | + |
| 37 | +v(0, 1) = 0 |
| 38 | +v(1, 1) = 0 |
| 39 | +v(2, 1) = 0 |
| 40 | +v(3, 1) = 0 |
| 41 | + |
| 42 | +For k = 1 To chain |
| 43 | + |
| 44 | + For i = 0 To 3 |
| 45 | + For j = 0 To 3 |
| 46 | + v(i, 1) = v(i, 1) + (v(j, 0) * M(j + 1, i + 1)) |
| 47 | + Next j |
| 48 | + Next i |
| 49 | + |
| 50 | + For i = 0 To 3 |
| 51 | + v(i, 0) = v(i, 1) |
| 52 | + v(i, 1) = 0 |
| 53 | + Next i |
| 54 | + |
| 55 | + A = v(0, 0) |
| 56 | + T = v(1, 0) |
| 57 | + c = v(2, 0) |
| 58 | + G = v(3, 0) |
| 59 | + |
| 60 | + MsgBox "V(" & k & ")=[" & A & " | " & T & " | " & c & " | " & G & "]" |
| 61 | + |
| 62 | +Next k |
| 63 | + |
| 64 | +End Sub |
| 65 | + |
| 66 | + |
| 67 | +Function ExtractProb(ByVal s As String) |
| 68 | + |
| 69 | +Ea = "A" |
| 70 | +Et = "T" |
| 71 | +Eg = "G" |
| 72 | +Ec = "C" |
| 73 | + |
| 74 | +For i = 1 To 4 |
| 75 | + For j = 1 To 4 |
| 76 | + M(i, j) = 0 |
| 77 | + Next j |
| 78 | +Next i |
| 79 | + |
| 80 | +Ta = 0 |
| 81 | +Tt = 0 |
| 82 | +Tg = 0 |
| 83 | +Tc = 0 |
| 84 | + |
| 85 | +For i = 2 To Len(s) - 1 |
| 86 | + |
| 87 | + DI1 = Mid(s, i, 1) |
| 88 | + DI2 = Mid(s, i + 1, 1) |
| 89 | + |
| 90 | + If DI1 = Ea Then r = 1 |
| 91 | + If DI1 = Et Then r = 2 |
| 92 | + If DI1 = Eg Then r = 3 |
| 93 | + If DI1 = Ec Then r = 4 |
| 94 | + |
| 95 | + If DI2 = Ea Then c = 1 |
| 96 | + If DI2 = Et Then c = 2 |
| 97 | + If DI2 = Eg Then c = 3 |
| 98 | + If DI2 = Ec Then c = 4 |
| 99 | + |
| 100 | + M(r, c) = Val(M(r, c)) + 1 |
| 101 | + |
| 102 | + If DI1 = Ea Then Ta = Ta + 1 |
| 103 | + If DI1 = Et Then Tt = Tt + 1 |
| 104 | + If DI1 = Eg Then Tg = Tg + 1 |
| 105 | + If DI1 = Ec Then Tc = Tc + 1 |
| 106 | + |
| 107 | +Next i |
| 108 | + |
| 109 | +For i = 1 To 4 |
| 110 | + For j = 1 To 4 |
| 111 | + If i = 1 Then M(i, j) = Val(M(i, j)) / Ta |
| 112 | + If i = 2 Then M(i, j) = Val(M(i, j)) / Tt |
| 113 | + If i = 3 Then M(i, j) = Val(M(i, j)) / Tg |
| 114 | + If i = 4 Then M(i, j) = Val(M(i, j)) / Tc |
| 115 | + Next j |
| 116 | +Next i |
| 117 | + |
| 118 | +End Function |
| 119 | + |
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