From: Elliot Crosby-McCullough <elliot.cm@...>
Date: 2010-04-18T16:48:11+09:00
Subject: Re: Elegant Solution to a Seemingly Simple Problem?

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On 18 April 2010 08:23, Derek Cannon <novellterminator@gmail.com> wrote:

> Hello everyone. It's me: Derek, again! Sorry for writing a novel here,
> but I'd really appreciate some help.
>
> I'm still working on the same program -- a way to show valid course
> combinations for my school schedule, using an HTML file that contains
> all the courses for the semester.
>
> I have a rough draft copy of it working, but I'd like to see an example
> of a more elegant coding style than my own.
>
> Here's a (simplified) example of the data I'm working with:
>
> <tr>
>  <td>Intro to Programming<td> #title
>  <td>MW</td> #days
>  <td>9:00am-10:30am</td> #time
>  <td>Dr. Smith</td> # professor
> </tr>
> <tr>
>  <td>Intro to Knitting<td>
>  <td>TR</td>
>  <td>9:00am-10:30am</td>
>  <td>Dr. Mittens</td>
> </tr>
>
> Earlier, someone on the forum showed me a very elegant way to collect
> this information (I use Nokogiri). It was:
>
> doc = Nokogiri::HTML(open(url))
>
> raw_course_list = doc.css("tr").collect { |row|
>  row.css("td").collect { |column|
>    column.text.strip
>  }
> }
>
> This would give me an array of arrays in the format
> [[courseA,data,data], [courseB, data, data]].
>
> E.g., in this case it would yield:
> [["Intro to Programming", "MW", "9:00am-10:30am", "Dr. Smith"], ["Intro
> to Knitting", "TR", "9:00am-10:30am", "Dr. Mittens"]]
>
> This works perfectly, except in 3 main cases.
>
> *** Problem 1: The <tr> does not contain course information. (It's some
> irrelevant part of the HTML). In this case, I did the following:
> raw_course_data.reject! { |i| i.size != 4 }, would filtered out
> non-courses. Note: no tables without course data had the size of one
> with course data (in the non-simplified version, the size is actually
> much larger).
>
> So, already I think it's ugly coding! It firsts loads ALL <tr> contents
> into arrays, then rejects them after creation.
>
> *** Problem 2: In a few cases, some courses do not have specified days
> and times yet. In those cases, the course days reads "TBA" (to be
> announced), and there is no column for time. Thus, the array of such
> courses is 1 less than the normal expected case.
>
> E.g.:
>
> <tr>
>  <td>Algebra<td>
>  <td>TBA</td> # notice there is now 1 <td> for day/time now
>  <td>Dr. Calculator</td>
> </tr>
>
> Thus, I create ANOTHER time that Ruby goes back over the elements of
> raw_course_list again. This time, the code is put right before problem
> 1's fix:
>
> raw_course_list.each { |i|
>  if i.size == 3
>    i.insert(2, "")
>  end
> }
>
> So again, if an array has a size of 3, I figure it's a valid course,
> just with no time assigned, so I create a blank element between the day
> and professor, just to satisfy the Course class, which these array
> elements of the outer array will ultimately become. E.g. of call:
> Course.new(title, day, time, professor)
>
> *** Problem 3: Some rows of the HTML are actually a continued
> description of the course in the row above. For example, a course that
> has a lab might look like this:
>
> <tr>
>  <td>Chemistry /w Lab<td>
>  <td>TR</td>
>  <td>9:00am-10:30am</td>
>  <td>Dr. Chemicals</td>
> </tr>
> <tr>
>  <td><td> # Empty, since the above row provides the course name
>  <td>R</td> # Day of the lab
>  <td>11:00am-12:30pm</td> # Time of the lab
>  <td>Dr. Chemicals</td>  # Lab professor
> </tr>
>
> The good news is it's the same length as a normal class. So for this, I
> add a bit more code to problem 2's code (the each block), changing the
> each method to .each_with_index:
>
> raw_course_list.each_with_index { |i, index|
>  if i.size == 3
>    i.insert(2, "")
>  end
>
>  # NEW CODE FOR LABS (still working out the kinks, but hopefully I
> won't need this)
>  # lab will always have a size of 4 and a empty first element so:
>  if i[0].empty?
>    # add all the data from the lab to the previous course:
>    raw_course_list[index-1].push(i.each { |element| element })
>
>    # then remove lab from raw_course_list
>    raw_course_list.pop(index)
>
>    # index has to go back one to avoid skipping an element (since we
> popped one)
>    index -= 1
>  end
> }
>
> ==================================
>
> So there you have it. Can anyone think of a way where I can improve the
> quality and elegance of this code?
> --
> Posted via http://www.ruby-forum.com/.
>
>
Do you have any control over the HTML at all?  Some semantic HTML classes
would go a long way to simplifying this.

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