ODCostMatrixSolverProperties (arcpy.na)
Summary
Provides access to analysis properties from an origin-destination (OD) cost matrix network analysis layer. The GetSolverProperties function is used to obtain an ODCostMatrixSolverProperties object from an OD cost matrix network analysis layer.
Discussion
The ODCostMatrixSolverProperties object provides read and write access to all the analysis properties of an OD cost matrix network analysis layer. The object can be used to modify the desired analysis properties of the OD cost matrix layer, and the corresponding layer can be re-solved to determine the appropriate results. A new OD cost matrix layer can be created using the Make OD Cost Matrix Layer geoprocessing tool. Obtaining the ODCostMatrixSolverProperties object from a new OD cost matrix layer allows you to reuse the existing layer for subsequent analyses rather than create a new layer for each analysis, which can be slow.
After modifying the properties on the ODCostMatrixSolverProperties object, the corresponding layer can be immediately used with other functions and geoprocessing tools. There is no refresh or update of the layer required to honor the changes modified through the object.
Properties
| Property | Explanation | Data Type |
| accumulators (Read and Write) | Provides the ability to get or set a list of network cost attributes that are accumulated as part of the analysis. An empty list, [], indicates that no cost attributes are accumulated. | String |
| attributeParameters (Read and Write) | Provides the ability to get or set the parameterized attributes to be used in the analysis. The property returns a Python dictionary. The dictionary key is a two-value tuple consisting of the attribute name and the parameter name. The value for each item in the dictionary is the parameter value. Parameterized network attributes are used to model some dynamic aspect of an attribute's value. For example, a tunnel with a height restriction of 12 feet can be modeled using a parameter. In this case, the vehicle's height in feet should be specified as the parameter value. If the vehicle is taller than 12 feet, this restriction will then evaluate to true, thereby restricting travel through the tunnel. Similarly, a bridge could have a parameter to specify a weight restriction. Attempting to modify the attributeParameters property in place won't result in updated values. Instead, you should always use a new dictionary object to set values for the property. The following two code blocks demonstrate the difference between these two approaches. #Don't attempt to modify the attributeParameters property in place.
#This coding method won't work.
solverProps.attributeParameters[('HeightRestriction', 'RestrictionUsage')] = "PROHIBITED"
#Modify the attributeParameters property using a new dictionary object.
#This coding method works.
params = solverProps.attributeParameters
params[('HeightRestriction', 'RestrictionUsage')] = "PROHIBITED"
solverProps.attributeParameters = params
| Dictionary |
| defaultCutoff (Read and Write) |
Provides the ability to get or set the default impedance value at which to cut off searching for destinations for a given origin. A value of None is used to specify that no cutoff should be used. | Double |
| defaultTargetDestinationCount (Read and Write) | Provides the ability to get or set the number of destinations to find for each origin. A value of None is used to specify that all destinations should be found. | Integer |
| impedance (Read and Write) | Provides the ability to get or set the network cost attribute used as impedance. This cost attribute is minimized while determining the routes between origins and destinations. | String |
| outputPathShape (Read and Write) | Controls whether a straight line is generated between each origin-destination pair in the output OD cost matrix. The following is a list of possible values:
| String |
| restrictions (Read and Write) | Provides the ability to get or set a list of restriction attributes that are applied for the analysis. An empty list, [], indicates that no restriction attributes are used for the analysis. | String |
| solverName (Read Only) | Returns the name of the solver being referenced by the network analysis layer used to obtain the solver properties object. The property always returns the string value OD Cost Matrix Solver when accessed from a ODCostMatrixSolverProperties object. | String |
| timeOfDay (Read and Write) | Provides the ability to get or set the departure date and time from the origins. A value of None can be used to specify that no date and time should be used. Instead of using a particular date, a day of the week can be specified using the following dates:
For example, to specify that the route from each origin should start at 8:00 AM on Wednesday, specify the value as datetime.datetime(1900, 1, 3, 8,0,0). | DateTime |
| useHierarchy (Read and Write) | Controls the use of the hierarchy attribute while performing the analysis. The following is a list of possible values:
| String |
| uTurns (Read and Write) | Provides the ability to get or set the policy that indicates how the U-turns at junctions that could occur during network traversal between stops are being handled by the solver. The following is a list of possible values:
| String |
Code Sample
The script shows how to update an OD cost matrix network analysis layer to find all destinations within a five-minute cutoff value. It assumes that an OD cost matrix layer called Store Accessibility has been created in a new map document based on the tutorial network dataset for San Francisco region.
#Get the OD cost matrix layer object from a layer named "Store Accessibility" in
#the table of contents
odLayer = arcpy.mapping.Layer("Store Accessibility")
#Get the solver properties object from the OD cost matrix layer
solverProps = arcpy.na.GetSolverProperties(odLayer)
#Update the properties for the OD cost matrix layer using the solver properties
#object
solverProps.defaultCutoff = 5
solverProps.defaultTargetDestinationCount = None