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When I compile and run the program I get an error:
Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object.
at ElevationModel.ReadDem(String inFileName)
at Program.Main()
using System;
using System.IO;
class GridPoint
{
private int row;
private int column;
public GridPoint( int row, int column)
{
this. row = row;
this. column = column;
}
public int Row
{
get{return row;}
}
public int Column
{
get{return column;}
}
public override string ToString()
{
return (String.Format("{0,4}{1,4}",row,column));
}
}
class ElevationModel
{
private string title;
private double[ , ] elevations = null;
private int row;
private int column;
public ElevationModel(string inFileName)
{
ReadDem(inFileName);
}
public string Title
{
get{return title;}
}
public int Rows
{
get{return row;}
}
public int Columns
{
get{return column;}
}
public double Elevation(int row, int column)
{
return elevations[row,column];
}
private void ReadDem(string inFileName)
{
StreamReader inStream = new StreamReader(inFileName);
title = inStream.ReadLine();
string line;
string [] splittedLine;
row = int.Parse(inStream.ReadLine());
column = int.Parse(inStream.ReadLine());
for(int i = 0; i< row; i++)
{
line = inStream.ReadLine();
splittedLine = line.Split(',');
for (int j = 0; j < column; j++)
{
elevations[i, j] = double.Parse(splittedLine[j]);
}
}
inStream.Close();
}
public void WriteDem(string outFileName)
{
StreamWriter outStream = new StreamWriter(outFileName);
outStream.WriteLine(title);
outStream.WriteLine("{0}", row);
outStream.WriteLine("{0}", column);
for (int i = 0; i < row; i++)
{
for (int h = 0; h < column; h++)
{
outStream.WriteLine(elevations [i,h]);
}
outStream.WriteLine();
}
outStream.Close();
}
public GridPoint[] Outliers()
{
int rowSize = Rows;
int columnSize = Columns;
GridPoint[] temp;
int countOutliers = 0;
for (int i = 1; i < rowSize - 1; i++)
{
for (int j = 1; j < columnSize - 1; j++)
{
double average = (elevations[i - 1, j - 1] + elevations[i, j - 1] +
elevations[i + 1, j - 1] + elevations[i - 1, j] + elevations[i + 1, j]
+ elevations[i - 1, j + 1] + elevations[i, j + 1] + elevations[i + 1, j + 1]) / 8;
if (Math.Abs(average - Elevation(i, j)) > 100)
{ countOutliers++; }
}
}
temp = new GridPoint[countOutliers];
int position = 0;
for (int i = 1; i < rowSize - 1; i++)
{
for (int j = 1; j < columnSize - 1; j++)
{
double average = (elevations[i - 1, j - 1] + elevations[i, j - 1] +
elevations[i + 1, j - 1] + elevations[i - 1, j] + elevations[i + 1, j]
+ elevations[i - 1, j + 1] + elevations[i, j + 1] + elevations[i + 1, j + 1]) / 8;
if (Math.Abs(average - elevations[i, j]) > 100)
{
temp[position] = new GridPoint(i, j);
position++;
}
}
}
return temp;
}
public void SmoothOutliers(int row, int column)
{
double average = (elevations[row - 1, column - 1] + elevations[row, column - 1] +
elevations[row + 1, column - 1] + elevations[row - 1, column] + elevations[row + 1, column]
+ elevations[row - 1, column + 1] + elevations[row, column + 1] + elevations[row + 1, column + 1]) / 8;
elevations[row, column] = Math.Round(10 * average) / 10;
}
public double Area(double elevation)
{
int count = 0;
double area = 0;
foreach (double a in elevations)
if (a <= elevation)
count++;
area = count * 0.1 * 0.1;
return area;
}
public double Volume(double elevation)
{
double volume = 0;
foreach (double s in elevations)
if (s <= elevation)
//add up the volumes of each square (0.1 km by 0.1 km)
//Elevation is in m, convert to km by dividing it by 1000.
volume += 0.1 * 0.1 * elevation / 1000; //in km cubed.
return volume;
}
}
class Program
{
static void Main()
{
string filename = "TahoeDEM.csv";
ElevationModel model = new ElevationModel(filename);
GridPoint point = new GridPoint(model.Rows, model.Columns);
GridPoint[] grid = model.Outliers();
foreach (GridPoint d in grid)
{
Console.WriteLine(d);
}
}
}
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