Finding the maximum and using it outside the IF

jrwarwick · October 17th, 2003, 12:50 AM

Hello!
Here is my headache:
I am transforming xml into svg to create a bar graph.
In order to set up the graph axes I need to figure the maximum value to be displayed so that it will be accommodated by the graph space.

Cut down input xml:
<report>
<item value="7"/>
<item value="4"/>
<item value="2"/>
<item value="2"/>
<item value="1"/>
</report>
XSL:
<xsl:for-each select="item">
<xsl:sort data-type="number" order="ascending" select="@value"/>
<xsl:if test="position()=1">
<xsl:variable name="maxy" select="ceiling(@value div 10) * 10"/>
<xsl:variable name="stepy" select="($ymax - $ymin) div $maxy"/>
</xsl:if>
</xsl:for-each>

Now the stepy variable is only available inside the 'if 'block and therefore I can only use it to measure the relative length of the largest item bar to draw; all the other bars cant get this unit length value to measure their own bars.
How can I retrieve the maximum value so that it is usable in the rest of the template??
I believe this sort of info gathering is necessary in many many applications surely it is possible!

pgtips · October 17th, 2003, 03:54 AM

You just need to write the max to a variable with stylesheet scope. The way to do that is set-up a template which calc's the max and call that template from within an <xsl:variable> definition. Here's an example:

Code:

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

  <xsl:variable name="maxNum">
    <xsl:call-template name="getMax">
      <xsl:with-param name="nodes" select="/report/item"/>
    </xsl:call-template>
  </xsl:variable>
  ...

  <xsl:template name="getMax">
    <xsl:param name="nodes"/>
    <xsl:choose>
      <xsl:when test="not($nodes)">NaN</xsl:when>
      <xsl:otherwise>
        <xsl:for-each select="$nodes">
          <xsl:sort data-type="number" order="descending"/>
          <xsl:if test="position() = 1">
            <xsl:value-of select="number(.)"/>
          </xsl:if>
        </xsl:for-each>
      </xsl:otherwise>
    </xsl:choose>
  </xsl:template>
  ...

hth
Phil

joefawcett · October 17th, 2003, 03:59 AM

I haven't tried this for your example bit normally you put the variable declaration around the test:

Code:

<xsl:variable name="maxValue">
  <xsl:for-each select="item">
    <xsl:sort data-type="number" order="ascending" select="@value"/>
    <xsl:if test="position()=1"> 
      <xsl:value-of select="@value"/>
    </xsl:if>
  </xsl:for-each>
</xsl:variable>

Then use $maxValue to produce your other variables.

--

Joe