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Re: Grouping problem?

2003-04-22 14:18:47
Unfortunately, this does not produce the right result in the general case.

Consider:

<root>
  <ele sum="3"/>
  <ele sum="4"/>
  <ele sum="2"/>
  <ele sum="10"/>
  <ele sum="1"/>
  <ele sum="5"/>
  <ele sum="1"/>
  <ele sum="2"/>
</root>


The result produced by your transformation is:

<root>
  <ele sum="3"></ele>
  <ele sum="4"></ele>
  <ele sum="2"></ele>
  <br />
  <ele sum="10"></ele>
  <ele sum="1"></ele>
  <br />
  <ele sum="5"></ele>
  <ele sum="1"></ele>
  <ele sum="2"></ele>
</root>

The second group above has a sum of 11.


There is a recursive solution. It can be obtained by translating in XSLT the
following brief Haskell solution:


cutBy :: (Num a, Ord a) => a -> [[a]] -> [a] -> [[a]]

cutBy z yss [] = yss

cutBy z (yss) (x:xs)

| sum (last yss) + x < z + 1 = cutBy z ( init yss ++ [last yss ++ [x]]) xs

| otherwise = cutBy z ( yss ++ [[x]]) xs

This works as follows:

MYExamples> cutBy 10 [ [] ]   [3, 4, 2, 10, 7, 5, 1, 2]

[[3,4,2], [10], [7], [5,1,2]]

MYExamples> cutBy 10 [ [] ]  [3, 4, 2, 10, 1, 7, 5, 1, 2]

[[3,4,2], [10], [1,7], [5,1,2]]

MYExamples>


The beauty of Haskell is that because of lazy evaluation we could have
infinite lists and the above function is a transformation of one stream into
another -- e.g. we could model operations on a conveyor line.


Of course the above will not work, because we are using last().

But this will work with streams:

cutBy :: (Num a, Ord a) => a -> [[a]] -> [a] -> [[a]]

cutBy z yss [] = yss

cutBy z (ys:yss) (x:xs)

| sum ys + x < z + 1 = cutBy z ((x : ys) : yss ) xs

| otherwise = cutBy z ([x] : ys : yss ) xs


MYExamples> cutBy 10 [ [] ] [3, 4, 2, 10, 7, 5, 1, 2]

[[2,1,5], [7], [10], [2,4,3]]

MYExamples> cutBy 10 [ [] ] [3, 4, 2, 10, 1, 7, 5, 1, 2]

[[2,1,5], [7,1], [10], [2,4,3]]

MYExamples>


=====
Cheers,

Dimitre Novatchev.
http://fxsl.sourceforge.net/ -- the home of FXSL

"Benjamin Farrow" <lovinjess(_at_)hotmail(_dot_)com> wrote in message
news:Law15-F58cDioalzvzy0000e86f(_at_)hotmail(_dot_)com(_dot_)(_dot_)(_dot_)
Well perhaps I've found a solution...it appears to be working anyhow.  Any
comments would be welcome.

<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>

  <xsl:key name="groupByTen"
           match="ele"
           use="ceiling(sum(preceding-sibling::ele/@sum|@sum) div 10)"/>

  <xsl:template match="/">
    <xsl:apply-templates select="node()|@*"/>
  </xsl:template>

  <xsl:template match="ele">
    <xsl:variable name="sum"
select="sum(preceding-sibling::ele/@sum|@sum)"/>
    <xsl:if test="generate-id(key('groupByTen',ceiling($sum div 10))[1]) =
generate-id(.) and
                  position() != 1">
      <br/>
    </xsl:if>
    <xsl:copy>
      <xsl:apply-templates select="node()|@*"/>
    </xsl:copy>
  </xsl:template>

  <xsl:template match="node()|@*">
    <xsl:copy>
      <xsl:apply-templates select="node()|@*"/>
    </xsl:copy>
  </xsl:template>

</xsl:stylesheet>





From: "Benjamin Farrow" <lovinjess(_at_)hotmail(_dot_)com>
Reply-To: xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com
To: xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com
Subject: [xsl] Grouping problem?
Date: Tue, 22 Apr 2003 12:06:02 -0700

All,
 I don't know how to explain my problem in words very concisely, so I'll
try with a simplified example.

SourceXML:
<root>
 <ele sum="3"/>
 <ele sum="4"/>
 <ele sum="2"/>
 <ele sum="10"/>
 <ele sum="7"/>
 <ele sum="5"/>
 <ele sum="1"/>
 <ele sum="2"/>
</root>

Desired Output:
<root>
 <ele sum="3"/>
 <ele sum="4"/>
 <ele sum="2"/>
 <br/>          <!-- next element makes total greater than 10 -->
 <ele sum="10"/>
 <br/>          <!-- next element makes total greater than 20 -->
 <ele sum="7"/>
 <br/>          <!-- next element makes total greater than 30 -->
 <ele sum="5"/>
 <ele sum="1"/>
 <ele sum="2"/>
</root>

I'm trying to break apart the ele element when the sum total of preceding
siblings and self is greater than the increment of 10 by putting an
element
to denote the break.

I've tried some crazy tests with mod and div and I've looked over the
Muenchian grouping, but I still can't come up with a way to arbitrarily
set
the break points.  I know there is a solution and I get close, but I just
can't get around it.

Here is my template (also have the standard identity template) with which
I'm trying to get this working.  I just can't figure out the if test for
this though.

XSL:
 <xsl:template match="ele">
   <xsl:variable name="sum"
select="sum(preceding-sibling::ele/@sum|@sum)"/>
   <xsl:if test="$sum &gt; (floor($sum div 10) * 10)">
     <br/>
   </xsl:if>
   <xsl:copy>
     <xsl:apply-templates select="node()|@*"/>
   </xsl:copy>
 </xsl:template>

Thanks in advance,
 Benjamin


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