Question

I have some XML documents:

events.xml:

<?xml version="1.0" encoding="UTF-8"?>
<events>
  <event>
    <id>9</id> 
    <region>3</region> 
    <region>12</region> 
    <region>29</region> 
  </event>
  <event> 
    <id>7</id> 
    <region>1</region>
    <region>12345</region>
  </event>
  <event> 
    <id>3</id> 
    <region>12</region>
    <region>39</region> 
    <region>56</region> 
  </event>
  <event> 
    <id>8</id> 
    <region>8</region> 
    <region>123</region> 
    <region>456</region>
  </event>
  <event> 
    <id>4</id> 
    <region>999</region> 
    <region>888</region> 
    <region>777</region> 
  </event>
</events>

exposure.xml:

<?xml version="1.0" encoding="UTF-8"?>
<companies>
  <company> 
    <id>6</id>
    <region>3</region>
    <region>9</region> 
    <region>8</region>
    <region>11111</region> 
    <region>12</region> 
  </company>
  <company> 
    <id>4</id> 
    <region>3</region> 
    <region>6</region> 
    <region>7</region> 
    <region>12345</region> 
  </company>
  <company> 
    <id>9</id> 
    <region>1</region> 
    <region>2</region> 
    <region>3</region> 
  </company>
</companies>

I need to write a program to process the two files:

For each event in the event file the program should write out the
event number followed by the set of companies it affects in the
exposure file. The list of companies should be written out in
ascending company number.

Given the sample files, the output should be something like this:

 9 4 6 9

 8 6

 7 4 9

 3 6

Answer 1

Have a little bit of LINQ in your life.

var eventsDoc = XDocument.Load(@"events.xml");
var exposureDoc = XDocument.Load(@"exposure.xml");

var companies =
   (from c in exposureDoc.Descendants("company")
    let id = (int)c.Element("id")
    orderby id
    select new
    {
        Id = id,
        Regions = new HashSet<int>(
            from r in c.Elements("region")
            select (int)r),
    }).ToList();
var events =
    from e in eventsDoc.Descendants("event")
    let id = (int)e.Element("id")
    orderby id descending
    select new
    {
        Id = id,
        Regions = from r in e.Elements("region")
                  select (int)r,
    };
foreach (var evnt in events)
{
    var affectedCompanies =
        from c in companies
        where c.Regions.Overlaps(evnt.Regions)
        select c.Id;
    if (affectedCompanies.Any())
        Console.WriteLine("{0} {1}", evnt.Id, String.Join(" ", affectedCompanies));
}

If you’re using .NET 3.5, you’ll need to change the query in the body of the loop a bit.

var affectedCompanies =
   (from c in companies
    where c.Regions.Overlaps(evnt.Regions)
    select c.Id.ToString()).ToArray();