Preceding sibling in XML - xpath

Question

I have a XML data like that:
<items>
<data>2</data>
<listElement>
<amounts>
<period_id>1</period_id>
<amount>5</amount>
</amounts>
<amounts>
<period_id>2</period_id>
<amount>6</amount>
</amounts>
<amounts>
<period_id>3</period_id>
<amount>7</amount>
</amounts>
<amounts>
<period_id>8</period_id>
<amount>89</amount>
</amounts>
</listElement>
</items>
<items>
<data></data>
<listElement>
<amounts>
<period_id>4</period_id>
<amount>55</amount>
</amounts>
<amounts>
<period_id>5</period_id>
<amount>9</amount>
</amounts>
<amounts>
<period_id>6</period_id>
<amount>20</amount>
</amounts>
<amounts>
<period_id>7</period_id>
<amount>80</amount>
</amounts>
</listElement>
</items>
In my xsl code I'm inside a node amounts and I want to get the value of the tag "data" who is parent of this tag amounts?
I'm using xalan with xslt1.0 and apache fop
Note: I tried with:
<xsl:value-of select="preceding-sibling::*data[normalize-space(.)]">
</xsl:value-of>
But still wrong.

Answer 1

in my xsl code i'm inside a node
amounts and i want to get the value of
the tag "data" who is parent of this
tag amounts
Do note that data element is a child of items (amount grandparent) in your sample.
Use this:
../../data
Also this:
preceding::data[1]
But it must be guaranteed that there is going to be one data in every items.
If you really want to use preceding-sibling axis then:
../preceding-sibling::data

Answer 2

From the context of an amounts element:
../preceding-sibling::data[1]
The following stylesheet copies the preceding data element into each amounts element, leaving the rest of the document unchanged:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="#*|node()">
<xsl:copy>
<xsl:apply-templates select="#*|node()" />
</xsl:copy>
</xsl:template>
<xsl:template match="amounts">
<xsl:copy>
<xsl:apply-templates select="#*|node()" />
<xsl:copy-of select="../preceding-sibling::data[1]" />
</xsl:copy>
</xsl:template>
</xsl:stylesheet>
It produces the following output when applied to your source document:
<root>
<items>
<data>2</data>
<listElement>
<amounts>
<period_id>1</period_id>
<amount>5</amount>
<data>2</data>
</amounts>
<amounts>
<period_id>2</period_id>
<amount>6</amount>
<data>2</data>
</amounts>
<amounts>
<period_id>3</period_id>
<amount>7</amount>
<data>2</data>
</amounts>
<amounts>
<period_id>8</period_id>
<amount>89</amount>
<data>2</data>
</amounts>
</listElement>
</items>
<items>
<data />
<listElement>
<amounts>
<period_id>4</period_id>
<amount>55</amount>
<data />
</amounts>
<amounts>
<period_id>5</period_id>
<amount>9</amount>
<data />
</amounts>
<amounts>
<period_id>6</period_id>
<amount>20</amount>
<data />
</amounts>
<amounts>
<period_id>7</period_id>
<amount>80</amount>
<data />
</amounts>
</listElement>
</items>
</root>