Get max attribute value from XML using LINQ

问题:

I have the following XML file. I want to get Max("NR") using LINQ. Could anyone help me to do this? I know how to do this for nodes, but attributes made me confused... :S

<?xml version="1.0" encoding="utf-8"?>
<SMPyramid LayerName="qwe" LayerPath="D:\#PYRAMID\qwe" Extension=".png" Meters="100000" RasterSize="4000">
  <Level NR="0" RasterXSize="512" RasterYSize="512" LastTileXSize="416" LastTileYSize="416" MinX="400000" MaxX="500000" MinY="1200000" MaxY="1300000" ScaleFactor="25" TilesCountX="8" TilesCountY="8" />
  <Level NR="1" RasterXSize="512" RasterYSize="512" LastTileXSize="323" LastTileYSize="323" MinX="400000" MaxX="499980.9024" MinY="1200019.0976" MaxY="1300000" ScaleFactor="34.679466666666663" TilesCountX="6" TilesCountY="6" />
  <Level NR="2" RasterXSize="512" RasterYSize="512" LastTileXSize="414" LastTileYSize="414" MinX="400000" MaxX="499738.14613333333" MinY="1200261.8538666666" MaxY="1300000" ScaleFactor="69.358933333333326" TilesCountX="3" TilesCountY="3" />
  <Level NR="3" RasterXSize="512" RasterYSize="512" LastTileXSize="206" LastTileYSize="206" MinX="400000" MaxX="499599.42826666665" MinY="1200400.5717333332" MaxY="1300000" ScaleFactor="138.71786666666665" TilesCountX="2" TilesCountY="2" />
  <Level NR="4" RasterXSize="358" RasterYSize="358" LastTileXSize="358" LastTileYSize="358" MinX="400000" MaxX="499321.99253333331" MinY="1200678.0074666666" MaxY="1300000" ScaleFactor="277.4357333333333" TilesCountX="1" TilesCountY="1" />
</SMPyramid>

回答1:

You treat attributes exactly the same way you would as nodes. So for example:

int maxNr = doc.Descendants("Level")
               .Max(x => (int) x.Attribute("NR"));

Note that that will give you the maximum value of NR, not the Level element which contains that number. For that, you'd want to either use OrderByDescending(...).First() or use MaxBy from MoreLINQ.

回答2:

XDocument xDoc = XDocument.Load(@" your XML file path ");
int maxNr = xDoc.Root.Elements().Max(x => (int)x.Element("NR"));

After you specify the file path, you can get "NR" using the Element.