How to get sum of elements by it's position. I have below XML and wanted to get sum of DonneeRensCompl by position using XSLT - xslt-1.0

Question

I have below code and wanted to get sum of DonneeRensCompl by it's position. Example Position1 = 3.60 (1.30+ 2.30 = 3.60) likewise for all possible positions.
<DATA_DS>
<R>
<Annee>2021</Annee>
<CaseRensCompl>
<CodeRensCompl>235</CodeRensCompl>
<DonneeRensCompl>1.30</DonneeRensCompl>
</CaseRensCompl>
<CaseRensCompl>
<CodeRensCompl>B-1</CodeRensCompl>
<DonneeRensCompl>10650.00</DonneeRensCompl>
</CaseRensCompl>
<CaseRensCompl>
<CodeRensCompl>RZ-RJ</CodeRensCompl>
<DonneeRensCompl>10650.00</DonneeRensCompl>
</CaseRensCompl>
</R>
<R>
<Annee>2021</Annee>
<CaseRensCompl>
<CodeRensCompl>235</CodeRensCompl>
<DonneeRensCompl>2.30</DonneeRensCompl>
</CaseRensCompl>
<CaseRensCompl>
<CodeRensCompl>RZ-CA</CodeRensCompl>
<DonneeRensCompl>10650.00</DonneeRensCompl>
</CaseRensCompl>
</R>
</DATA_DS>

Answer 1

If you don't know in advance the number of positions, then you must increment the position in a loop until there are no nodes in the current position:
XSLT 1.0
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:template match="/DATA_DS">
<root>
<xsl:call-template name="sum-by-positions"/>
</root>
</xsl:template>
<xsl:template name="sum-by-positions">
<xsl:param name="i" select="1"/>
<xsl:variable name="cases" select="//CaseRensCompl[$i]" />
<xsl:if test="$cases">
<sum position="{$i}">
<xsl:value-of select="format-number(sum($cases/DonneeRensCompl), '#,##0.00')"/>
</sum>
<!-- recursive call -->
<xsl:call-template name="sum-by-positions">
<xsl:with-param name="i" select="$i + 1"/>
</xsl:call-template>
</xsl:if>
</xsl:template>
</xsl:stylesheet>
Applied to your input example, this will produce:
Result
<?xml version="1.0" encoding="UTF-8"?>
<root>
<sum position="1">3.60</sum>
<sum position="2">21,300.00</sum>
<sum position="3">10,650.00</sum>
</root>
To understand how this works, read this note in the XPath 1.0 specification:
NOTE: The location path //para[1] does not mean the same as the location path /descendant::para[1]. The latter selects the first descendant para element; the former selects all descendant para elements that are the first para children of their parents.