dot spatial sample code

7/29/2019 Dot Spatial Sample Code

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Sample code that demonstrates how to get the value of

a single cell in an attribute table.

using DotSpatial.Data;

privatevoid btnBuffer_Click(object sender, EventArgs e)

{

FeatureSet fs = new FeatureSet();

fs.FillAttributes();

fs.Open("C:\\Temp\\roads.shp");

DataTable dt = fs.DataTable;

for(int row = 0; row < dt.Rows.Count; row++)

{

object val = dtOriginal.Rows[row]["LENGTH"];

}

}

Sample code for loop through a Feature Set's attribute

table and get all the values

using System.Windows.Forms;

using DotSpatial.Topology;



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{




DataTable dtOriginal = fs.DataTable;

for(int row = 0; row < dtOriginal.Rows.Count; row++)

{

object[] original = dtOriginal.Rows[row].ItemArray;

}

}

This code demonstrates how to open an existing

shapefile as a new feature set using the

System.Spatial.Desktop library.


publicvoid OpeningFS()

{

//Declare a new feature set


//Pass in the file path for the standard shapefile that will be opened



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}

// create a new shape file

Shapefile s = new Shapefile();

// define the feature type for this file

FeatureSet fs = new FeatureSet( FeatureType.Polygon );

// Add Some Columns

fs.DataTable.Columns.Add( new DataColumn( "ID", typeof( int )));

fs.DataTable.Columns.Add( new DataColumn( "Text", typeof( string )));

// create a geometry (square polycon)

List vertices = new List();

vertices.Add(new Coordinate(0, 0));

vertices.Add( new Coordinate( 0,100 ));



Polygon geom = new Polygon( vertices );

// add the geometry to the featureset.

IFeature feature = fs.AddFeature(geom);

// now the resulting features knows what columns it has


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// add values for the columns

feature.DataRow.BeginEdit();

feature.DataRow"ID" = 1;

feature.DataRow"Text" = "Hello World";

feature.DataRow.EndEdit();

// save the feature set

fs.SaveAs("d:\\test.shp", true);

This code generates a random linestring from a

coordinate array using the Geometry library then

creates a line feature using the desktop library.


using DotSpatial.Geometries;

namespace SampleCode

{

publicpartialclass Form1 : Form

{

public Form1()

{

InitializeComponent();


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}

privatevoid button1_Click(object sender, EventArgs e)

{

//Creates a random number generator

Random rnd = new Random();

//creates a new coordiante array

Coordinate[] c = new Coordinate[36];

//for loop that will generate 36 random numbers

for(int i = 0; i < 36; i++)

{

c[i] = new Coordinate((rnd.NextDouble() * 360) - 180, (rnd.NextDouble()

* 180) - 90);

}

//creates a linestring from the coordinate array

LineString ls = new LineString(c);

//creates a feature from the linestring

Feature f = new Feature(ls);

FeatureSet fs = new FeatureSet(f.FeatureType);

fs.Features.Add(f);

}

}


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This code demonstrates how to open an existing

shapefile as a new feature set using the

System.Spatial.Desktop library and then buffer the

feature set.

using System.Spatial.Data;


{






//An IFeatureSet that contains the factory that will buffer the feature set

IFeatureSet iF = fs.Buffer(10, true);

//Saves the buffered feature set as a new file.

iF.SaveAs("C:\\Temp\roads_buffer.shp", true);

}

Sample code that demonstrates how to get the number

of rows in a feature set.


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using System.Windows.Forms;



{




double numRows = fs.NumRows();

}

Create random points, then move them around.

This example was a test case for a bug fix on 11/7/2010. Make sure you have downloaded something more recent than

changeset e91fbe2d79ca or else the "move" operation listed here will not work. To run this, create two buttons. The firstbutton adds the points. The second button moves the points to a slightly different random location. Pressing the move

button sequentially should cause the points to appear to move around randomly. This sample is also part of the

"TestViewer" application that is in the "Demo Projects" folder of the source code repository.


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//using DotSpatial.Data;

//using DotSpatial.Symbology;

//using DotSpatial.Topology;

//using System.Drawing;

privatevoid AddPoints()

{

// Create the featureset if one hasn't been created yet.

if(_myPoints == null) _myPoints = new FeatureSet(FeatureType.Point);


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// Assume background layers have been added, and get the current map

extents.

double xmin = map1.Extents.Minimum.X;

double xmax = map1.Extents.Maximum.X;

double ymin = map1.Extents.Minimum.Y;

double ymax = map1.Extents.Maximum.Y;

// Randomly generate 10 points that are in the map extent


for(int i = 0; i < 10; i++)

{

double x = xmin + rnd.NextDouble() * (xmax - xmin);

double y = ymin + rnd.NextDouble() * (ymax - ymin);

Coordinate c = new Coordinate(x, y);

_myPoints.Features.Add(c);

}

// Add a layer to the map, and we know it is a point layer so cast it specifically.

IMapPointLayer pointLayer = map1.Layers.Add(_myPoints) as

IMapPointLayer;


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// Control what the points look like through a symbolizer (or

pointLayer.Symbology for categories)

if(pointLayer != null)

{

pointLayer.LegendText = "MovingPoints";

pointLayer.Symbolizer = new PointSymbolizer(Color.Blue,

PointShape.Ellipse, 7);

}

}

privatevoid MovePoints()

{


foreach(IFeature feature in _myPoints.Features)

{

// Coordinates can be updated geographically like

// feature.Coordinates[0].X += (rnd.NextDouble() - .5);

// feature.Coordinates[0].Y += (rnd.NextDouble() - .5);

// Or controled in pixels with the help of the map

Point pixelLocation = map1.ProjToPixel(feature.Coordinates[0]);


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// Control movement in terms of pixels

int dx = Convert.ToInt32((rnd.NextDouble() - .5) * 50);// shift left or

right 5 pixels

int dy = Convert.ToInt32((rnd.NextDouble() - .5) * 50);// shift up or

down 5 pixels

pixelLocation.X = pixelLocation.X + dx;

pixelLocation.Y = pixelLocation.Y + dy;

// Convert the pixel motions back to geographic motions.

Coordinate c = map1.PixelToProj(pixelLocation);

feature.Coordinates[0] = c;

}

// Refresh the cached representation because we moved points around.

map1.MapFrame.Invalidate();

map1.Invalidate();

}

Sample code that demonstrates how to create a Multi

Polygon Feature Set


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{


Polygon[] pg = new Polygon[100];

Feature f = new Feature();


for(int i = 0; i < 100; i++)

{

Coordinate center = new Coordinate((rnd.Next(50) * 360) - 180,

(rnd.Next(60) * 180) - 90);

Coordinate[] coord = new Coordinate[50];

for(int ii = 0; ii < 50; ii++)

{

coord[ii] = new Coordinate(center.X + Math.Cos((ii * 10) * Math.PI /

10), center.Y + (ii * 10) * Math.PI / 10);

}

coord[35] = new Coordinate(coord[0].X, coord[0].Y);

pg[i] = new Polygon(coord);

fs.Features.Add(pg[i]);

}

fs.SaveAs("C:\\Temp\\test.shp", true);


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}

Sample code that demonstrates how to create a new

Multi Point Feature Set




{





for(int i = 0; i < 50; i++)

{

c[i] = new Coordinate((rnd.Next(0, 50) + 360) - 90, (rnd.NextDouble() *

360) - 180);

fs.Features.Add(c[i]);

}


}

Union Intersecting Shapes in a FeatureSet

This example shows how to use a newly added extension method that allows for intersecting shapes in the same Shapefile


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to be Unioned, but leaving shapes that don't overlap unchanged.

publicvoid UnionShapes()

{


fs.Open();

IFeatureSet result = fs.UnionShapes(ShapeRelateType.Intersecting);

SaveFileDialog sfd = new SaveFileDialog();

sfd.Filter = "*Shapefiles (*.shp)|*.shp";

if(sfd.ShowDialog() != DialogResult.OK) return;

result.SaveAs(sfd.FileName, true);

}


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Sample code that demonstrates how to open an

existing shapefile and save that shapefile with a new

file name.



{





//Saves the open shapefile

fs.SaveAs("C:\\Temp\\roads_test.shp", true);

}

Sample code that demonstrates how to create a Multi

Line Feature Set




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{





{


for(int i = 0; i < 36; i++)

{

coord[i] = new Coordinate((rnd.NextDouble() * 360) - 180,

(rnd.NextDouble() * 180) - 90);

}

LineString ls = new LineString(coord);

f = new Feature(ls);

fs.Features.Add(f);

}


}

Sample code to project a point using the ESRI Projection File

VB.Net Sample Code

Imports DotSpatial.Projections


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'Sample code that will conduct a reprojection by reading in the ESRI.prj file

PrivateSub btnProjection_Click(senderAsObject, e As EventArgs)

'declares a new ProjectionInfo for the startind and ending coordinate systems

'sets the start GCS to WGS_1984

Dim pStart As ProjectionInfo =

KnownCoordinateSystems.Geographic.World.WGS1984

Dim pESRIEnd AsNew ProjectionInfo()

'declares the point(s) that will be reprojected

Dim xy AsDouble() = NewDouble(1) {}

Dim z AsDouble() = NewDouble(0) {}

'initiates a StreamReader to read the ESRI .prj file

Dim re As StreamReader = File.OpenText("C:\Program Files\ArcGIS\Coordinate

Systems\Projected Coordinate Systems\UTM\WGS 1984\WGS 1984 UTM Zone 1N.prj")

'sets the ending PCS to the ESRI .prj file

pESRIEnd.ReadEsriString(re.ReadLine())

'calls the reprojection function

Reproject.ReprojectPoints(xy, z, pStart, pESRIEnd, 0, 1)

MessageBox.Show("Points have been projected successfully.")

EndSub

Sample code that demonstrates how to read a prog4

string and then project a point


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C# Code

using DotSpatial.Projections;

//Code that allows the user to input a Proj4 string and reproject a WGS 1984 GCS

to a Proj4 PCS

privatevoid btnProjection_Click(object sender, EventArgs e)

{

//Declares a new ProjectionInfo and sets it to GCS_WGS_1984

ProjectionInfo pStart = new ProjectionInfo();

pStart = KnownCoordinateSystems.Geographic.World.WGS1984;

//Declares a new ProjectionInfo and allows the user to directly input a Proj4

sring

ProjectionInfo pEnd = new ProjectionInfo("+proj=aea +lat_1=20

+lat_2=-23 +lat_0=0 +lon_0=25 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84

+units=m +no_defs ");

//Declares the point to be project, starts out as 0,0

double[] xy = newdouble[2];

double[] z = newdouble[1];

//calls the reproject function and reprojects the points

Reproject.ReprojectPoints(xy, z, pStart, pEnd, 0, 1);

MessageBox.Show("Reprojection is compelte.");

}

VB.net Code


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Imports DotSpatial.Projections

'Code that allows the user to input a Proj4 string and reproject a WGS 1984 GCS to a Proj4

PCS

PrivateSub btnProjection_Click(senderAsObject, e As EventArgs)

'Declares a new ProjectionInfo and sets it to GCS_WGS_1984

Dim pStart AsNew ProjectionInfo()

pStart = KnownCoordinateSystems.Geographic.World.WGS1984

'Declares a new ProjectionInfo and allows the user to directly input a Proj4 sring

Dim pEnd AsNew ProjectionInfo("+proj=aea +lat_1=20 +lat_2=-23 +lat_0=0

+lon_0=25 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs ")

'Declares the point to be project, starts out as 0,0

Dim xy AsDouble() = NewDouble(1) {}

Dim z AsDouble() = NewDouble(0) {}

'calls the reproject function and reprojects the points

Reproject.ReprojectPoints(xy, z, pStart, pEnd, 0, 1)

MessageBox.Show("Reprojection is compelte.")

EndSub

This code will add a geographic coordinate system (GCS) to a feature set that does not

contain a GCS.

VB Sample Code:

Imports System.Spatial.Projections


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'Code for defining a geographic coordinate system for a feature set

PrivateSub BbtnDefineGeographicProjection_Click(ByVal senderAs System.Object,

ByVal e As System.EventArgs) Handles BbtnDefineGeographicProjection.Click

Dim fs AsNew FeatureSet

Dim CopyFS AsNew FeatureSet

Dim dest As ProjectionInfo

'Get's the first layer in the Table of Contents

fs = MapControl.Layers.Item(0).DataSet

'Copies the selected layer to a new feature set

'Prevents the original file from being edited

CopyFS.CopyFeatures(fs, True)

dest = KnownCoordinateSystems.Geographic.World.WGS1984

'Adds the geographic coordinate system to the feature set

CopyFS.Projection = dest

'Saves the feature set

CopyFS.SaveAs("C:\Temp\US_Cities_GCS_WGS1984.shp" , True)

MessageBox.Show("The feature was successfully been projected.")

EndSub


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C# Sample Code:

//Code for defining a geographic coordinate system for a feature set

privatevoid BbtnDefineGeographicProjection_Click(System.Object sender,

System.EventArgs e)

{


FeatureSet CopyFS = new FeatureSet();

ProjectionInfo dest = default(ProjectionInfo);

//Get's the first layer in the Table of Contents

fs = MapControl.Layers.Item(0).DataSet;

//Copies the selected layer to a new feature set

//Prevents the original file from being edited

CopyFS.CopyFeatures(fs, true);

dest = KnownCoordinateSystems.Geographic.World.WGS1984;

//Adds the geographic coordinate system to the feature set

CopyFS.Projection = dest;

//Saves the feature set

CopyFS.SaveAs("C:\\Temp\\US_Cities_GCS_WGS1984.shp" , true);


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MessageBox.Show("The feature was successfully been projected.");

}

This code demonstrates the method for declaring a new coordinate and creating a point

from that coordinate.


using DotSpatial.Common;

privatevoid btnCoord_Click(object sender, EventArgs e)

{

//creates a new coordinate

Coordinate c = new Coordinate(2.4, 2.4);

//passes the coordinate to a new point

Point p = new Point(c);

//displayes the new point's x and y coordiantes

MessageBox.Show("Point p is: x= " + p.X + " & y= " + p.Y);

}

Creating a new linestring and calculating the length



privatevoid btnLineString_Click(object sender, EventArgs e)

{


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//creates a new coordinate array

Coordinate[] coords = new Coordinate[36];

//creates a random point variable


//a for loop that generates a new random X and Y value and feeds those

values into the coordinate array

for(int i = 0; i < 36; i++)

{

coords[i] = new Coordinate((rnd.NextDouble() * 360) - 180,


}

//creates a new linstring from the array of coordinates

LineString ls = new LineString(coords);

//new variable for the length of the linstring

Double length;

length = ls.Length;

//Displays the length of the linstring

MessageBox.Show("The length of the linstring is: " + length);

}

Sample code that demonstrates the creation of a new polygon from random points and

calculating the area




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privatevoid btnPolygon_Click(object sender, EventArgs e)

{

//creates a new coordinate array


//creates a random point variable


//Creates the center coordiante for the new polygon

Coordinate center = new Coordinate((rnd.NextDouble() * 360) - 180,


//a for loop that generates a new random X and Y value and feeds those

values into the coordinate array

for(int i = 0; i < 10; i++)

{

coords[i] = new Coordinate(center.X + Math.Cos((i * 2) * Math.PI / 18),

center.Y + (i * 2) * Math.PI / 18);

}

//creates a new polygon from the coordinate array

Polygon pg = new Polygon(coords);

//new variable for the area of the polgyon

Double area;

area = pg.Area;

//displays the area of the polygon

MessageBox.Show("The Area of the polygon is: " + area);

}


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Sample code showing how to generate a polygon from random points that contains a hole.


using DotSpatial.Topology.Geometries;

publicvoid PolgygonHolesSC()

{

//Defines a new coordinate array


//Defines a new random number generator


//defines a randomly generated center for teh polygon



for(int i = 0; i < 19; i++)

{

//generates random coordinates and adds those coordinates to the array


center.Y + (i * 10) * Math.PI / 10);

}

//sets the last coordinate equal to the first, this 'closes' the polygon

coords[19] = new Coordinate(coords[0].X, coords[0].Y);

//defines a new LingRing from the coordinates

LinearRing Ring = new LinearRing(coords);


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//Repeates the process, but generates a LinearRing with a smaller area, this

will be the hole in the polgyon

Coordinate[] coordshole = new Coordinate[20];

for(int i = 0; i < 20; i++)

{

coordshole[i] = new Coordinate(center.X + Math.Cos((i * 10) * Math.PI /

20), center.Y + (i * 10) * Math.PI / 20);

}

coordshole[19] = new Coordinate(coordshole[0].X, coordshole[0].Y);

LinearRing Hole = new LinearRing(coordshole);

//This steps addes the hole LinerRing to a ILinearRing Array

//A Polgyon can contain multiple holes, thus a Array of Hole is required

ILinearRing[] Holes = new ILinearRing[1];

Holes[0] = Hole;

//This passes the Ring, the polygon shell, and the Holes Array, the holes

Polygon pg = new Polygon(Ring, Holes);

}

Sample code that demonstrates how to create a new mulitpolygon from randomly

generated coordinates




{


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Polygon[] pg = new Polygon[50];

for(int i = 0; i < 50; i++)

{





{

coord[ii] = new Coordinate(center.X + Math.Cos((ii * 10) * Math.PI /

10), center.Y + (ii * 10) * Math.PI / 10);

}

coord[35] = new Coordinate(coord[0].X, coord[0].Y);

pg[i] = new Polygon(coord);

}

MultiPolygon mpg = new MultiPolygon(pg);

}

Sample code that demonstrates how to create a multilinestring from randomly generated

coordinates.



publicvoid samplecode()

{


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MultiLineString Mls = new MultiLineString();

LineString[] ls = new LineString[40];


{


for(int i = 0; i < 36; i++)

{

coord[i] = new Coordinate((rnd.NextDouble() * 360) - 180,


}

ls[ii] = new LineString(coord);

}

Mls = new MultiLineString(ls);

}

Sample code that demonstrates how to buffer a randomly generated point.




{

Coordinate coords = new Coordinate();



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coords = new Coordinate((rnd.NextDouble() * 360) - 180, (rnd.NextDouble()

* 180) - 90);

Point p = new Point(coords);

//This will get the area of the buffer.

double area = p.Buffer(500).Area;

}

Sample that demonstrates how to create a multipoint from randomly generated

coordinates




{



for(int i = 0; i < 36; i++)

{

c[i] = new Coordinate((rnd.NextDouble() + 360) - 180, (rnd.NextDouble()

* 180) - 90);

}

MultiPoint Mps = new MultiPoint(c);

}

Sample code that will generate random an array of coordinates, creates a linestring from

the array of coordinates, and calculates the length of the linestring.


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publicvoid PolgygonHolesSC()

{

//Creates a coordinate arrary




//A for loop that will generate random coordinate's and add those coordinates

to the array

for(int i = 0; i < 36; i++)

{

coords[i] = new Coordinate((rnd.NextDouble() * 360) - 180,


}

//Creates a linestring from the array of coordinates

LineString ls = new LineString(coords);

//Calculates the length of the linestring

Double length;

length = ls.Length;

}


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Sample code that will generate a coordinate array, create a polygon from the coordinate

array, and calculate the area of the polygon.



{

//Creates a new array of coordinates




//Createa a center point for the polygon



//A For Loop that will randomly create coordinates and feeds the coordinates

into the array of coordiantes

for(int i = 0; i < 19; i++)

{


center.Y + (i * 10) * Math.PI / 10);

}

//Set the last coordinate equal to the first coordinate in the array, thus

'closing' the polygon

coords[19] = new Coordinate(coords[0].X, coords[0].Y);

//Creates a new polygon from the coordinate array


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Polygon pg = new Polygon(coords);

//Determines that area of the polygon

Double area = pg.Area;

}

dot spatial sample code

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