Comments on: Doesn’t look like a number, but it is http://enoriver.net/index.php/2009/04/23/doesnt-look-like-a-number-but-it-is/ computing for fun and profit Wed, 18 Apr 2012 00:10:24 +0000 hourly 1 http://wordpress.org/?v=3.3.2 By: Gabi Huiber http://enoriver.net/index.php/2009/04/23/doesnt-look-like-a-number-but-it-is/comment-page-1/#comment-720 Gabi Huiber Mon, 27 Apr 2009 17:24:29 +0000 http://enoriver.net/?p=665#comment-720 You do get it. There are a couple of things I left unsaid and that introduced some ambiguity. The gist of it is that var_4 is conceptually different. var_1 through var_3 are actual measurements. For example, if this were a file of subscribers to a certain newspaper, var_1 could be the amount of their bill. var_4, on the other hand, is a count of non-zero instances of these measurements. You could add the zero measurements, and you're right that it wouldn't change the result, but the formula is clearer if it only consists of the logical conditions that describe what you're trying to count and nothing else. I spun this off a bigger job. I had several files and they had different ranges of these var_'s, and gaps were also possible -- for example, a file would have var_1 through var_7, another only var_2 and var_3, etc. I had to count the non-zero instances of whatever var_'s there were and write code that would work across all these files. That exercise might be worth a post of its own. You do get it. There are a couple of things I left unsaid and that introduced some ambiguity. The gist of it is that var_4 is conceptually different. var_1 through var_3 are actual measurements. For example, if this were a file of subscribers to a certain newspaper, var_1 could be the amount of their bill. var_4, on the other hand, is a count of non-zero instances of these measurements. You could add the zero measurements, and you're right that it wouldn't change the result, but the formula is clearer if it only consists of the logical conditions that describe what you're trying to count and nothing else.

I spun this off a bigger job. I had several files and they had different ranges of these var_'s, and gaps were also possible -- for example, a file would have var_1 through var_7, another only var_2 and var_3, etc. I had to count the non-zero instances of whatever var_'s there were and write code that would work across all these files. That exercise might be worth a post of its own.

]]> By: Jess http://enoriver.net/index.php/2009/04/23/doesnt-look-like-a-number-but-it-is/comment-page-1/#comment-718 Jess Mon, 27 Apr 2009 16:36:00 +0000 http://enoriver.net/?p=665#comment-718 Okay, I think I get it, but I'm worried that I don't get it. Why would you leave out the zeroes in the sum variable? They don't add or subtract anything. Would creating a variable that sums non-missing values be another useful example? Or maybe I'm not getting it. :) Okay, I think I get it, but I'm worried that I don't get it. Why would you leave out the zeroes in the sum variable? They don't add or subtract anything. Would creating a variable that sums non-missing values be another useful example? Or maybe I'm not getting it. :)

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