1 | MODULE sort_mod |
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2 | |
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3 | ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
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4 | ! Sorting algorithms |
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5 | ! ~~~~~~~~~~~~~~~~~~~ |
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6 | ! Contains quicksort (qsort) and insertion sort (isort) |
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7 | ! -> Sorts an array (real only for now) by increasing values |
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8 | ! -> If wanted, output indexes of permutations if you want to apply the same sorting to other arrays |
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9 | ! ( this is quicker than having other arrays going through the whole process ) |
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10 | ! |
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11 | ! TODO : Extend interface to integers - Enable decreasing order |
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12 | ! |
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13 | ! Author : J. Vatant d'Ollone - 2018 |
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14 | ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
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15 | |
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16 | IMPLICIT NONE |
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17 | |
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18 | INTERFACE qsort |
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19 | MODULE PROCEDURE qsort_r |
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20 | MODULE PROCEDURE qsort_outp_r |
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21 | END INTERFACE qsort |
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22 | |
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23 | INTERFACE isort |
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24 | MODULE PROCEDURE isort_r |
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25 | MODULE PROCEDURE isort_outp_r |
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26 | END INTERFACE isort |
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27 | |
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28 | CONTAINS |
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29 | |
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30 | ! 1-pivot quicksort |
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31 | RECURSIVE SUBROUTINE qsort_r(A,n) |
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32 | |
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33 | IMPLICIT NONE |
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34 | |
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35 | ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
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36 | ! I/O |
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37 | !logical, intent(in) :: o !! Order T=increasing/F=decreasing |
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38 | integer, intent(in) :: n !! Size of array |
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39 | real, dimension(n), intent(inout) :: A !! Array to sort |
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40 | |
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41 | ! Local variables |
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42 | integer :: left, right |
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43 | real :: random |
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44 | real :: pivot |
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45 | real :: temp |
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46 | integer :: marker |
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47 | ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
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48 | |
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49 | if (n > 1) then |
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50 | |
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51 | call random_number(random) |
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52 | pivot = A(int(random*real(n-1))+1) ! random pivot (not best performance, but avoids worst-case) |
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53 | left = 0 |
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54 | right = n + 1 |
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55 | |
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56 | do while (left < right) |
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57 | right = right - 1 |
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58 | do while (A(right) > pivot) |
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59 | right = right - 1 |
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60 | enddo |
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61 | left = left + 1 |
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62 | do while (A(left) < pivot) |
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63 | left = left + 1 |
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64 | enddo |
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65 | if (left < right) then |
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66 | temp = A(left) |
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67 | A(left) = A(right) |
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68 | A(right) = temp |
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69 | endif |
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70 | enddo |
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71 | |
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72 | if (left == right) then |
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73 | marker = left + 1 |
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74 | else |
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75 | marker = left |
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76 | endif |
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77 | |
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78 | call qsort(A(:marker-1), marker-1) |
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79 | call qsort(A(marker:), n-marker+1) |
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80 | |
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81 | endif |
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82 | |
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83 | END SUBROUTINE qsort_r |
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84 | |
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85 | |
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86 | ! 1-pivot quicksort + output array of permutations |
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87 | RECURSIVE SUBROUTINE qsort_outp_r(A,n,P) |
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88 | |
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89 | IMPLICIT NONE |
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90 | |
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91 | ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
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92 | ! I/O |
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93 | !logical, intent(in) :: o !! Order T=increasing/F=decreasing |
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94 | integer, intent(in) :: n !! Size of array |
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95 | integer, dimension(n), intent(inout) :: P !! Output array of permutations |
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96 | real, dimension(n), intent(inout) :: A !! Array to sort |
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97 | |
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98 | ! Local variables |
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99 | integer :: i |
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100 | integer :: left, right |
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101 | real :: random |
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102 | real :: pivot |
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103 | real :: tempA |
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104 | integer :: tempP |
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105 | integer :: marker |
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106 | ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
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107 | |
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108 | if (n > 1) then |
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109 | |
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110 | call random_number(random) |
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111 | pivot = A(int(random*real(n-1))+1) ! random pivot (not best performance, but avoids worst-case) |
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112 | left = 0 |
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113 | right = n + 1 |
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114 | |
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115 | do while (left < right) |
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116 | right = right - 1 |
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117 | do while (A(right) > pivot) |
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118 | right = right - 1 |
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119 | enddo |
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120 | left = left + 1 |
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121 | do while (A(left) < pivot) |
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122 | left = left + 1 |
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123 | enddo |
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124 | if (left < right) then |
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125 | tempA = A(left) |
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126 | tempP = P(left) |
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127 | A(left) = A(right) |
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128 | P(left) = P(right) |
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129 | A(right) = tempA |
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130 | P(right) = tempP |
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131 | endif |
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132 | enddo |
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133 | |
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134 | if (left == right) then |
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135 | marker = left + 1 |
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136 | else |
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137 | marker = left |
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138 | endif |
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139 | |
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140 | call qsort(A(:marker-1), marker-1, P(:marker-1)) |
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141 | call qsort(A(marker:), n-marker+1, P(marker:)) |
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142 | |
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143 | endif |
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144 | |
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145 | END SUBROUTINE qsort_outp_r |
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146 | |
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147 | |
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148 | ! Insertion sort |
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149 | SUBROUTINE isort_r(A,n) |
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150 | IMPLICIT NONE |
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151 | |
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152 | INTEGER, INTENT(in) :: n !! Size of array |
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153 | REAL, DIMENSION(n), INTENT(inout) :: A !! Array to sort |
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154 | |
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155 | INTEGER :: i, j |
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156 | REAL :: x |
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157 | |
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158 | DO i = 2, n |
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159 | x = a(i) |
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160 | j = i - 1 |
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161 | DO WHILE (j >= 1) |
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162 | IF (a(j) <= x) EXIT |
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163 | a(j + 1) = a(j) |
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164 | j = j - 1 |
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165 | ENDDO |
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166 | a(j + 1) = x |
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167 | ENDDO |
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168 | END SUBROUTINE isort_r |
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169 | |
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170 | |
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171 | ! Insertion sort + output array of permutations |
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172 | SUBROUTINE isort_outp_r(A,n,P) |
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173 | IMPLICIT NONE |
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174 | |
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175 | INTEGER, INTENT(in) :: n !! Size of array |
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176 | INTEGER, DIMENSION(n), INTENT(inout) :: P !! Output array of permutations |
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177 | REAL, DIMENSION(n), INTENT(inout) :: A !! Array to sort |
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178 | |
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179 | INTEGER :: i, j, px |
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180 | REAL :: x |
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181 | |
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182 | DO i = 2, n |
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183 | x = a(i) |
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184 | px = p(i) |
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185 | j = i - 1 |
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186 | DO WHILE (j >= 1) |
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187 | IF (a(j) <= x) EXIT |
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188 | a(j + 1) = a(j) |
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189 | p(j + 1) = p(j) |
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190 | j = j - 1 |
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191 | ENDDO |
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192 | a(j + 1) = x |
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193 | p(j + 1) = px |
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194 | ENDDO |
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195 | END SUBROUTINE isort_outp_r |
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196 | |
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197 | |
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198 | END MODULE sort_mod |
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199 | |
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