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Viewing changes to examples/helpers/country_code_helper.py

  • Committer: gak
  • Date: 2009-03-15 07:34:55 UTC
  • Revision ID: git-v1:2ce2bd2a423b1305ad2ad81c72b69c004fecec05
Added some example helpers for MapChart

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examples/helpers/country_code_helper.py
 
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class CountryCodes:
 
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    '''
 
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    This is just a helper to generate useful data files. It isn't directly used
 
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    in these examples.
 
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    '''
 
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    def __init__(self):
 
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        self.parse_codes_data()   
 
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    def parse_codes_data(self):
 
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        lines = open('iso3166-1-a2.txt', 'rb').read().split('\n')
 
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        self.codes = dict([ a.split(' ', 1) for a in lines[:-1] ])
 
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    def get_country_code_from_name(self, guess_name):
 
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        best_score = 100
 
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        best_code = None
 
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        for code, name in self.codes.items():
 
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            score = self.levenshtein(guess_name, name)
 
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            if score < best_score:
 
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                best_score = score
 
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                best_code = code
 
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        return best_code
 
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    def levenshtein(self, a, b):
 
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        "Calculates the Levenshtein distance between a and b."
 
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        n, m = len(a), len(b)
 
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        if n > m:
 
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            # Make sure n <= m, to use O(min(n,m)) space
 
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            a,b = b,a
 
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            n,m = m,n
 
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        current = range(n+1)
 
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        for i in range(1,m+1):
 
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            previous, current = current, [i]+[0]*n
 
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            for j in range(1,n+1):
 
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                add, delete = previous[j]+1, current[j-1]+1
 
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                change = previous[j-1]
 
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                if a[j-1] != b[i-1]:
 
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                    change = change + 1
 
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                current[j] = min(add, delete, change)
 
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        return current[n]
 
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