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Jan 22nd, 2018
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  1. trainingData=[['slashdot','USA','yes',18,'None'],
  2. ['google','France','yes',23,'Premium'],
  3. ['google','France','yes',23,'Basic'],
  4. ['google','France','yes',23,'Basic'],
  5. ['digg','USA','yes',24,'Basic'],
  6. ['kiwitobes','France','yes',23,'Basic'],
  7. ['google','UK','no',21,'Premium'],
  8. ['(direct)','New Zealand','no',12,'None'],
  9. ['(direct)','UK','no',21,'Basic'],
  10. ['google','USA','no',24,'Premium'],
  11. ['slashdot','France','yes',19,'None'],
  12. ['digg','USA','no',18,'None'],
  13. ['google','UK','no',18,'None'],
  14. ['kiwitobes','UK','no',19,'None'],
  15. ['digg','New Zealand','yes',12,'Basic'],
  16. ['slashdot','UK','no',21,'None'],
  17. ['google','UK','yes',18,'Basic'],
  18. ['kiwitobes','France','yes',19,'Basic']]
  19.  
  20. class decisionnode:
  21.  
  22. def __init__(self,col=-1,value=None,results=None,tb=None,fb=None):
  23. self.col=col
  24. self.value=value
  25. self.results=results
  26. self.tb=tb
  27. self.fb=fb
  28.  
  29. def sporedi_broj(row,column,value):
  30. return row[column]>=value
  31.  
  32. def sporedi_string(row,column,value):
  33. return row[column]==value
  34.  
  35. def divideset(rows,column,value):
  36.  
  37. split_function=None
  38. if isinstance(value,int) or isinstance(value,float):
  39.  
  40. split_function=sporedi_broj
  41. else:
  42.  
  43. split_function=sporedi_string
  44.  
  45.  
  46. set1=[row for row in rows if split_function(row,column,value)] # za sekoj row od rows za koj split_function vrakja true
  47. set2=[row for row in rows if not split_function(row,column,value)] # za sekoj row od rows za koj split_function vrakja false
  48. return (set1,set2)
  49.  
  50.  
  51.  
  52. def uniquecounts(rows):
  53. results={}
  54. for row in rows:
  55. # The result is the last column
  56. r=row[len(row)-1]
  57. if r not in results:
  58. results[r]=0
  59. results[r]+=1
  60. return results
  61.  
  62.  
  63. def entropy(rows):
  64. from math import log
  65. log2=lambda x:log(x)/log(2)
  66. results=uniquecounts(rows)
  67. # Now calculate the entropy
  68. ent=0.0
  69. for r in results.keys():
  70. p=float(results[r])/len(rows)
  71. ent=ent-p*log2(p)
  72. return ent
  73.  
  74. def buildtree(rows,scoref=entropy):
  75. if len(rows)==0: return decisionnode()
  76. current_score=scoref(rows)
  77.  
  78.  
  79. best_gain=0.0
  80. best_criteria=None
  81. best_sets=None
  82.  
  83. column_count=len(rows[0])-1
  84. for col in range(0,column_count):
  85.  
  86. column_values={}
  87. for row in rows:
  88. column_values[row[col]]=1
  89.  
  90.  
  91. for value in column_values.keys():
  92. (set1,set2)=divideset(rows,col,value)
  93.  
  94.  
  95. p=float(len(set1))/len(rows)
  96. gain=current_score-p*scoref(set1)-(1-p)*scoref(set2)
  97. if gain>best_gain and len(set1)>0 and len(set2)>0:
  98. best_gain=gain
  99. best_criteria=(col,value)
  100. best_sets=(set1,set2)
  101.  
  102.  
  103. if best_gain>0:
  104. trueBranch=buildtree(best_sets[0])
  105. falseBranch=buildtree(best_sets[1])
  106. return decisionnode(col=best_criteria[0],value=best_criteria[1],tb=trueBranch, fb=falseBranch)
  107. else:
  108. return decisionnode(results=uniquecounts(rows))
  109.  
  110. def printtree(tree,indent='',level=0):
  111.  
  112. if tree.results!=None:
  113. print str(tree.results)
  114. else:
  115. # Print the criteria
  116. print str(tree.col)+':'+str(tree.value)+'? ' + 'Level=%d' % (level)
  117. # Print the branches
  118. print indent+'T->',
  119. printtree(tree.tb,indent+' ',level+1)
  120. print indent+'F->',
  121. printtree(tree.fb,indent+' ',level+1)
  122.  
  123. if __name__ == "__main__":
  124. # referrer='slashdot'
  125. # location='US'
  126. # readFAQ='no'
  127. # pagesVisited=19
  128. # serviceChosen='None'
  129.  
  130. referrer=input()
  131. location=input()
  132. readFAQ=input()
  133. pagesVisited=input()
  134. serviceChosen=input()
  135.  
  136. testCase=[referrer, location, readFAQ, pagesVisited, serviceChosen]
  137. trainingData.append(testCase)
  138. t=buildtree(trainingData)
  139. printtree(t)
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