How to: Find a Union of Two Location Paths (XPath-LINQ to XML)
XPath allows you to find the union of the results of two XPath location paths.
The XPath expression is:
//Category|//Price
You can achieve the same results by using the Concat<TSource> standard query operator.
Example
This example finds all of the Category elements and all of the Price elements, and concatenates them into a single collection. Note that the LINQ to XML query calls InDocumentOrder<T> to order the results. The results of the XPath expression evaluation are also in document order.
This example uses the following XML document: Sample XML File: Numerical Data (LINQ to XML).
XDocument data = XDocument.Load("Data.xml");
// LINQ to XML query
IEnumerable<XElement> list1 =
data
.Descendants("Category")
.Concat(
data
.Descendants("Price")
)
.InDocumentOrder();
// XPath expression
IEnumerable<XElement> list2 = data.XPathSelectElements("//Category|//Price");
if (list1.Count() == list2.Count() &&
list1.Intersect(list2).Count() == list1.Count())
Console.WriteLine("Results are identical");
else
Console.WriteLine("Results differ");
foreach (XElement el in list1)
Console.WriteLine(el);
Dim data As XDocument = XDocument.Load("Data.xml")
' LINQ to XML query
Dim list1 As IEnumerable(Of XElement) = _
data...<Category>.Concat(data...<Price>).InDocumentOrder()
' XPath expression
Dim list2 As IEnumerable(Of XElement) = _
data.XPathSelectElements("//Category|//Price")
If list1.Count() = list2.Count() And _
list1.Intersect(list2).Count() = list1.Count() Then
Console.WriteLine("Results are identical")
Else
Console.WriteLine("Results differ")
End If
For Each el As XElement In list1
Console.WriteLine(el)
Next
This example produces the following output:
Results are identical
<Category>A</Category>
<Price>24.50</Price>
<Category>B</Category>
<Price>89.99</Price>
<Category>A</Category>
<Price>4.95</Price>
<Category>A</Category>
<Price>66.00</Price>
<Category>B</Category>
<Price>.99</Price>
<Category>A</Category>
<Price>29.00</Price>
<Category>B</Category>
<Price>6.99</Price>