## Re: [xsl] Calculating cumulative values

 Subject: Re: [xsl] Calculating cumulative values From: "Dimitre Novatchev" Date: Sat, 3 Feb 2007 14:49:54 -0800
On 2/3/07, Andrew Welch <andrew.j.welch@xxxxxxxxx> wrote:

You can just use XPath here, no need for recursion:

```<xsl:template match="point">
<xsl:copy>
<xsl:copy-of select="@*"/>
<xsl:attribute name="y2">
<xsl:value-of select="sum(./@y1|preceding-sibling::point[@x =
current()/@x]/@y1)"/>
</xsl:attribute>
</xsl:copy>
</xsl:template>
```

```However evaluating this XPath expression repeatedly is O(N^2) and will
probably be slow for long lists.```

Here is a solution, using the FXSL function

f:scanl1()

This transformation:

```<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
xmlns:f="http://fxsl.sf.net/";
exclude-result-prefixes="f"
```

``` <xsl:import href="../f/func-scanlDVC.xsl"/>
<xsl:import href="../f/func-Operators.xsl"/>```

``` <!-- To be applied on testFunc-scanlDVC3.xml -->
<xsl:output omit-xml-declaration="yes" indent="yes"/>```

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

``` <xsl:template match="set">
<xsl:copy>
<xsl:copy-of select="@*"/>
<xsl:for-each-group select="point" group-by="@x">
<point x="{current-group()[1]/@x}" y="{.}"/>
</xsl:for-each>
</xsl:for-each-group>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>```

When applied against the originally provided xml document:

```<root id="theroot">
<set id="1">
<point x="1" y1="2" />
<point x="1" y1="3" />
<point x="1" y1="0" />
<point x="1" y1="2" />
<point x="1" y1="2" />
<point x="2" y1="3" />
<point x="2" y1="0" />
<point x="2" y1="2" />
<point x="3" y1="2" />
<point x="3" y1="3" />
<point x="3" y1="1" />
<point x="3" y1="2" />
<point x="3" y1="2" />
</set>
<set id="2">
<point x="1" y1="2" />
<point x="1" y1="3" />
<point x="1" y1="0" />
<point x="1" y1="2" />
<point x="2" y1="2" />
<point x="3" y1="2" />
<point x="3" y1="2" />
<point x="3" y1="2" />
</set>
<set id="n">
<point x="1" y1="2" />
<point x="1" y1="3" />
<point x="1" y1="2" />
<point x="2" y1="3" />
<point x="2" y1="0" />
<point x="2" y1="2" />
<point x="3" y1="3" />
</set>
</root>```

produces the wanted result:

```<root id="theroot">
<set id="1">
<point x="1" y="2"/>
<point x="1" y="5"/>
<point x="1" y="5"/>
<point x="1" y="7"/>
<point x="1" y="9"/>
<point x="2" y="3"/>
<point x="2" y="3"/>
<point x="2" y="5"/>
<point x="3" y="2"/>
<point x="3" y="5"/>
<point x="3" y="6"/>
<point x="3" y="8"/>
<point x="3" y="10"/>
</set>
<set id="2">
<point x="1" y="2"/>
<point x="1" y="5"/>
<point x="1" y="5"/>
<point x="1" y="7"/>
<point x="2" y="2"/>
<point x="3" y="2"/>
<point x="3" y="4"/>
<point x="3" y="6"/>
</set>
<set id="n">
<point x="1" y="2"/>
<point x="1" y="5"/>
<point x="1" y="7"/>
<point x="2" y="3"/>
<point x="2" y="3"/>
<point x="2" y="5"/>
<point x="3" y="3"/>
</set>
</root>```

```--
Cheers,
Dimitre Novatchev
---------------------------------------
Truly great madness cannot be achieved without significant intelligence.
---------------------------------------
To invent, you need a good imagination and a pile of junk
-------------------------------------
You've achieved success in your field when you don't know whether what
you're doing is work or play```