Source Code for Module ml.lib.scikit.features_file_utils

 1  ''' 
 2  Created on Aug 29, 2012 
 3   
 4  @author: desouza 
 5  ''' 
 6  import codecs 
 7  import numpy as np 
 8  import logging as log 
 9   
10 -def read_labels_file(path, delim, encoding='utf-8'): 
11      '''Reads the labels of each column in the training and test files (features  
12      and reference files). 
13       
14      @param path: the path of the labels file 
15      @param delim: the character used to separate the label strings. 
16      @param encoding: the character encoding used to read the file.  
17      Default is 'utf-8'. 
18       
19      @return: a list of strings representing each feature column. 
20      ''' 
21      labels_file = codecs.open(path, 'r', encoding) 
22      lines = labels_file.readlines() 
23       
24      if len(lines) > 1: 
25          log.warn("labels file has more than one line, using the first.") 
26       
27      if len(lines) == 0: 
28          log.error("labels file is empty: %s" % path) 
29       
30      labels = lines[0].strip().split(delim) 
31       
32      return labels 
33       
34       
35 -def read_reference_file(path, delim, encoding='utf-8'): 
36      """Parses the file that contains the references and stores it in a numpy array. 
37       
38         @param path the path of the file. 
39         @delim char the character used to separate values. 
40          
41         @return: a numpy array representing each instance response value 
42      """ 
43       
44      # reads the references to a vector 
45      refs_file = codecs.open(path, 'r', encoding) 
46      refs_lines = [] 
47      for line in refs_file: 
48          cols = line.strip().split(delim) 
49          refs_lines.append(cols[0]) 
50   
51      refs = np.asfarray(refs_lines) 
52       
53       
54      return refs 
55   
56   
57 -def read_features_file(path, delim, encoding='utf-8'): 
58      ''' 
59      Reads the features for each instance and stores it on an numpy array. 
60       
61      @param path: the path to the file containing the feature set. 
62      @param delim: the character used to separate the values in the file pointed by path. 
63      @param encoding: the character encoding used to read the file. 
64       
65      @return: an numpy array where the columns are the features and the rows are the instances. 
66      ''' 
67      # this method is memory unneficient as all the data is kept in memory 
68      feats_file = codecs.open(path, 'r', encoding) 
69      feats_lines = [] 
70      line_num = 0 
71      for line in feats_file: 
72          if line == "": 
73              continue 
74          toks = tuple(line.strip().split(delim)) 
75          cols = [] 
76          for t in toks: 
77              if t != '': 
78                  try: 
79                      cols.append(float(t)) 
80                  except ValueError as e: 
81                      log.error("%s line %s: %s" % (e, line_num, t)) 
82           
83          line_num += 1 
84          feats_lines.append(cols) 
85       
86      #    print feats_lines 
87      feats = np.asarray(feats_lines) 
88       
89      return feats 
90   
91   
92  if __name__ == '__main__': 
93      pass 
94