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courses:be5b33prg:homeworks:spam:step2 [2015/11/25 16:33]
xposik [Preparation]
courses:be5b33prg:homeworks:spam:step2 [2015/12/04 14:22]
svobodat [Specifications]
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 from collections import namedtuple from collections import namedtuple
  
-ConfMat = namedtuple('​ConfMat',​ 'tptn fp fn')+ConfMat = namedtuple('​ConfMat',​ 'tp tn fp fn')
 </​code>​ </​code>​
  
 Why do we need it? Why do we need it?
   * Function ''​compute_confusion_matrix()''​ represents the basis for evaluation of the filter performance.   * Function ''​compute_confusion_matrix()''​ represents the basis for evaluation of the filter performance.
-  * The function can be used in the following way:<code python>+ 
 +The function can be used in the following way. First, an example where both the input dictionaries are empty, i.e. we have no information about any email. 
 +<code python>
 >>>​ cm1 = compute_confusion_matrix({},​ {}) >>>​ cm1 = compute_confusion_matrix({},​ {})
 >>>​ print(cm1) >>>​ print(cm1)
 ConfMat(tp=0,​ tn=0, fp=0, fn=0) ConfMat(tp=0,​ tn=0, fp=0, fn=0)
-</​code>​or<code python>+</​code>​ 
 + 
 +In the following code, each of TP, TN, FP, FN cases happens exactly once: 
 + 
 +<code python>
 >>>​ truth_dict = {'​em1':​ '​SPAM',​ '​em2':​ '​SPAM',​ '​em3':​ '​OK',​ '​em4':'​OK'​} >>>​ truth_dict = {'​em1':​ '​SPAM',​ '​em2':​ '​SPAM',​ '​em3':​ '​OK',​ '​em4':'​OK'​}
 >>>​ pred_dict = {'​em1':​ '​SPAM',​ '​em2':​ '​OK',​ '​em3':​ '​OK',​ '​em4':'​SPAM'​} >>>​ pred_dict = {'​em1':​ '​SPAM',​ '​em2':​ '​OK',​ '​em3':​ '​OK',​ '​em4':'​SPAM'​}
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 </​code>​ </​code>​
  
-**Note**: You can expect ​that the dictionaries ​will have the same set of keysThink about the situation when the keys would be different: what shall the method do?+And in the last example, the predictions perfectly match the real classes, such that only TP and TN are nonzero: 
 + 
 +<code python>​ 
 +>>>​ truth_dict = {'​em1':​ '​SPAM',​ '​em2':​ '​SPAM',​ '​em3':​ '​OK',​ '​em4':'​OK'​} 
 +>>>​ pred_dict = {'​em1':​ '​SPAM',​ '​em2':​ '​SPAM',​ '​em3':​ '​OK',​ '​em4':'​OK'​} 
 +>>>​ cm2 = compute_confusion_matrix(truth_dict,​ pred_dict, pos_tag='​SPAM',​ neg_tag='​OK'​) 
 +>>>​ print(cm2) 
 +ConfMat(tp=2,​ tn=2, fp=0, fn=0) 
 +</​code>​ 
 + 
 +Of course, ​the input dictionaries ​may have a different number ​of items than 4. 
 + 
  
 >​{{page>​courses:​be5b33prg:​internal:​homeworks:​spam:​step2#​compute_confusion_matrix&​editbtn}} >​{{page>​courses:​be5b33prg:​internal:​homeworks:​spam:​step2#​compute_confusion_matrix&​editbtn}}
  
  
courses/be5b33prg/homeworks/spam/step2.txt · Last modified: 2015/12/04 14:22 by svobodat