Hamming to use wikipedia definition #44
Conversation
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This change goes from defining the hamming distance of strings of unequal length to whatever the shortest overlap is (unlikely to be correct), to raising an error. I would be fine with either raising an error, or simply removing the tests ("result is undefined for strings of unequal length"). @kotp the official definition is mathematical, and I haven't taken the time to dig into whether or not that definition includes some defined behavior for strings/bit vectors of unequal length. |
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I only mention it from your statement "Let's clean this up so that we're using the official definition." in Issue #31 which may or not be what you really want. |
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Yes, I understand. I was imprecise. I don't really want exercism to be particularly algorithmic -- there's already Euler Project for that. |
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Thinking about this some more, I would rather not raise errors in Hamming, since it is the first exercise on the ruby track of exercism. I'd rather leave it undefined (remove the tests), since then the discussion can talk about what happens when the inputs are of unequal length. There are enough very new programmers on the Ruby track that introducing error handling in the first problem might be a bit of a high barrier to getting their first win. |
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Thank you, everyone, for taking the time to discuss this, and for bearing with my confusion and indecision. I've gone ahead and removed the offending tests in master. |
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(on a sidenote) Comparing vectors of different length makes no mathematical sense whatsoever, so I wouldn't think it's mathematically defined. |
This removes the tests that define behavior for cases where the strings are of unequal length. Since the hamming problem is the first one on the Ruby track, and so many people who are new to programming start with the Ruby track, I didn't want to introduce error handling here. The wikipedia article about the Hamming distance says that the behavior is undefined if the strings are of unequal length. I don't necessarily think that this means that a particular implementation _shouldn't_ specify an error, only that it's OK to leave it undefined. This will also make it possible to bring up the idea of edge cases and error handling in the discussions on the site. Closes #44 and #31.
Issue #31