# Question about SequenceMatcher.quick_ratio

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## Question about SequenceMatcher.quick_ratio

 Hi, all. I am one of  translator of Python document. But I am not good at English well. I can't understand one sentence in: http://docs.python.org/library/difflib.html#difflib.SequenceMatcher.quick_ratio> This isn’t defined beyond that it is an upper bound on ratio(), and is faster to compute. I see that quick_ratio() calculates upper bound of ratio(). But I can't get what "this isn't defined beyond that" means. May someone explain this in easy sentence for me? -- INADA Naoki  <[hidden email]> _______________________________________________ Doc-SIG maillist  -  [hidden email] http://mail.python.org/mailman/listinfo/doc-sig
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## Re: Question about SequenceMatcher.quick_ratio

 INADA Naoki <[hidden email]> writes: > I am one of translator of Python document.  But I am not good at > English well.  I can't understand one sentence ... > >> This isn’t defined beyond that it is an upper bound on ratio(), and >> is faster to compute. The word "bound" works like this: a "bound" or "boundary" means a limit or edge, so often it gets used in math like this:     "I am not sure what the exact value of 'pi' is, but I have done some      work and established a lower bound of 3.0 and an upper bound of 3.2      for its true value." This means, more simply, that 'pi' lies "between 3.0 and 3.2", but math people have the specific names "lower bound" and "upper bound" for the limits that they work out for the value of an unknown or difficult-to- compute number. So when 'quick_ratio()' claims to return an "upper bound on ratio()", it means that it returns a number that 'ratio()' is guaranteed to be "less than"; it sets, in other words, an upper limit on what the actual value of  'ratio()' might be. So if 'quick_ratio()' returns 0.8, it means that 'ratio()' itself might be 0.8, or 0.6, or 0.003, or 0.00062, or even 0; that is, it might be any permissible ratio value (they run from 0 to 1) that is not more than 0.8 because 'quick_ratio()' has done some checking and is sure that the actual 'ratio()' is less than or equal to 0.8. So did my English make the docs any clearer?  Or am I just as confusing? :-) -- Brandon Craig Rhodes   [hidden email]   http://rhodesmill.org/brandon_______________________________________________ Doc-SIG maillist  -  [hidden email] http://mail.python.org/mailman/listinfo/doc-sig
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## Re: Question about SequenceMatcher.quick_ratio

 In reply to this post by INADA Naoki-2 On May 6, 2010, at 10:48 AM, INADA Naoki wrote: > Hi, all. > > I am one of  translator of Python document. > But I am not good at English well. > > I can't understand one sentence in: > http://docs.python.org/library/difflib.html#difflib.SequenceMatcher.quick_ratio> >> This isn’t defined beyond that it is an upper bound on ratio(), and   >> is faster to compute. > > I see that quick_ratio() calculates upper bound of ratio(). > But I can't get what "this isn't defined beyond that" means. > May someone explain this in easy sentence for me? I think it means that the implementation of quick_ratio() is not   defined in a lot of detail, except to say that the function will   return a value that is an upper bound of the value returned by   ratio().  So the value returned by ratio() will always be less than or   equal to the value returned by quick_ratio(), and quick_ratio() is   faster than ratio().  real_quick_ratio() has a similar relationship to   quick_ratio(). Doug _______________________________________________ Doc-SIG maillist  -  [hidden email] http://mail.python.org/mailman/listinfo/doc-sig
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## Re: Question about SequenceMatcher.quick_ratio

 Thank you, Branodn and  Doug for quick reply! The word "upper bound" is also used in Japan with mathematics. > I think it means that the implementation of quick_ratio() is not defined in > a lot of detail, except to say that the function will return a value that is > an upper bound of the value returned by ratio(). That's the answer I wanted!! I've got "This isn't defined beyond that" means "This method is not defined in detail more than". I've misread that "beyond" means "over the upper bound". Maybe, "more" is easier than "beyond" for non-native English readers. Thank you very well. -- INADA Naoki  <[hidden email]> _______________________________________________ Doc-SIG maillist  -  [hidden email] http://mail.python.org/mailman/listinfo/doc-sig
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## Re: Question about SequenceMatcher.quick_ratio

 On May 6, 2010, at 11:27 AM, INADA Naoki wrote: > Thank you, Branodn and  Doug for quick reply! > > The word "upper bound" is also used in Japan with mathematics. > >> I think it means that the implementation of quick_ratio() is not   >> defined in >> a lot of detail, except to say that the function will return a   >> value that is >> an upper bound of the value returned by ratio(). > > That's the answer I wanted!! > > I've got "This isn't defined beyond that" means > "This method is not defined in detail more than". > > I've misread that "beyond" means "over the upper bound". > Maybe, "more" is easier than "beyond" for non-native English > readers. I agree that the current English phrasing is confusing to non-native   speakers.  You should open a ticket in the tracker and ask for that   text to be clarified. Doug > > Thank you very well. > -- > INADA Naoki  <[hidden email]> > _______________________________________________ > Doc-SIG maillist  -  [hidden email] > http://mail.python.org/mailman/listinfo/doc-sig_______________________________________________ Doc-SIG maillist  -  [hidden email] http://mail.python.org/mailman/listinfo/doc-sig