Leveraging ArcPy in a .NET application

In this topic

• About ArcPy
• Leveraging ArcPy in .NET
• Using geometry as tool input
• Adding the Python application to the Path variable

About ArcPy

Leveraging ArcPy in .NET

• You can call any Python script (*.py) from .NET. This includes code that uses Python packages designed for analytical and mathematical purposes, such as R statistics, complex matrix algebra, SciPy, or any other script.
• Similarly, you can use simplified ArcPy functions as well. The following are several modules that you can take advantage of:
  • Mapping module - For more information, see Geoprocessing scripts for map document management and output. 
  • Geostatistical Analyst module - For more information, see A quick tour of the Geostatistical Analyst ArcPy classes.
  • Spatial Analyst module - For more information, see An overview of Spatial Analyst classes. 
  There are many classes in an ArcPy package that you can integrate in your code.
• You can use the .NET geoprocessor to execute a script tool that is implemented with Python. This is the way GIS analysts use it.

Using geometry as tool input

import arcpy

# Create an Array object.
#
array=arcpy.Array()

# List of coordinates.
#
coordList=['1.0;1.0','1.0;10.0','10.0;10.0','10.0;1.0']

# For each coordinate set, create a point object and add the x- and 
#   y-coordinates to the point object, then add the point object 
#   to the array object.
#
for coordPair in coordList:
    x, y=coordPair.split(";")
    pnt=arcpy.Point(x,y)
    array.add(pnt)

# Add in the first point of the array again to close the polygon boundary.
#
array.add(array.getObject(0))

# Create a polygon geometry object using the array object.
#
boundaryPolygon=arcpy.Polygon(array)

# Use the geometry to clip an input feature class.
#
arcpy.Clip_analysis("c:/data/rivers.shp", boundaryPolygon, "c:/data/rivers_clipped.shp")

// Executes a shell command synchronously.
// Example of command parameter value is
// "python " + @"C:\scripts\geom_input.py".
//
public static void ExecuteCommand(object command)
{
    try
    {
        // Create the ProcessStartInfo using "cmd" as the program to be run,
        // and "/c " as the parameters.
        // "/c" tells cmd that you want it to execute the command that follows,
        // then exit.
        System.Diagnostics.ProcessStartInfo procStartInfo=new
            System.Diagnostics.ProcessStartInfo("cmd", "/c " + command);

        // The following commands are needed to redirect the standard output.
        // This means that it will be redirected to the Process.StandardOutput StreamReader.
        procStartInfo.RedirectStandardOutput=true;
        procStartInfo.UseShellExecute=false;

        // Do not create the black window.
        procStartInfo.CreateNoWindow=true;

        // Now you create a process, assign its ProcessStartInfo, and start it.
        System.Diagnostics.Process proc=new System.Diagnostics.Process();
        proc.StartInfo=procStartInfo;
        proc.Start();

        // Get the output into a string.
        string result=proc.StandardOutput.ReadToEnd();

        // Display the command output.
        Console.WriteLine(result);
    }
    catch (Exception objException)
    {
        Console.WriteLine(objException.Message);
        // Log the exception and errors.
    }
}

' Executes a shell command synchronously.
' Example of command parameter value is
' "python " + "C:\scripts\geom_input.py".
'

Sub ExecuteCommandSync(ByVal Command As Object)
    
    Try
    
    ' Create the ProcessStartInfo using "cmd" as the program to be run,
    ' and "/c " as the parameters.
    ' "/c" tells cmd that you want it to execute the command that follows,
    ' then exit.
    Dim procStartInfo As System.Diagnostics.ProcessStartInfo=New System.Diagnostics.ProcessStartInfo("cmd", "/c " + Command)
    
    ' The following commands are needed to redirect the standard output.
    ' This means that it will be redirected to the Process.StandardOutput StreamReader.
    procStartInfo.RedirectStandardOutput=True
    procStartInfo.UseShellExecute=False
    procStartInfo.CreateNoWindow=True
    
    ' Now you create a process, assign its ProcessStartInfo, and start it.
    Dim proc As System.Diagnostics.Process=New System.Diagnostics.Process()
    proc.StartInfo=procStartInfo
    proc.Start()
    
    ' Get the output into a string.
    Dim result As String=proc.StandardOutput.ReadToEnd()
    
    ' Display the command output.
    Console.WriteLine(result)
    
    Catch ex As Exception
    Console.WriteLine(ex.Message)
    ' Log the exception and errors.
    
    End Try
    
End Sub

Adding the Python application to the Path variable

1. Right-click My Computer and click Properties. The System Properties dialog box appears.
2. On the System Properties dialog box, click the Advanced tab, then click the Environment Variables button. The Environment Variables dialog box appears as shown in the following screen shot:
   
   
   
3. On the Environment Variables dialog box, under the System variables section, double-click the Path variable. The Edit System Variable dialog box appears. Type the path of the Python application. See the following screen shot:
   
   
   
   In this example, Python is installed in the C:\Python26 directory location.  

• ESRI.ArcGIS.Geoprocessing