Allocation

Allocates a set of demand points (Customers) to user specified number of supply points (Facilities) out of a Facilities point dataset based on the Euclidian distance between the Customers and Facilities. In other words the function selects N Facilities out of K candidates to service a set of M Customer locations in such a way that each Customer is allocated to a single Facility (based on Euclidean distance) and the total distance between the Customers and selected Facilities is minimized.

The function uses heuristic vertex substitution algorithm modified from Teitz and Bart (1968) and can handle comparatively large problems (Number of Customers * Number Facilities < 5 Million)

Inputs:

Point feature layer representing the Facilities (Centers).
Facility name field (optional) - the values in this field are used to identify the facilities. If the field is not specified the FID will be used as a name
Facility type field (optional) - the values of this field indicate whether a specific facility must be included in the selected set of facilities. Values of "1", "Required", "Existing" will force the inclusion of the Facility in the selected set of facilities. If the field is not specified all facilities will be considered as equal in the selection algorithm.
Point feature layer representing the customers (demand points) that need to be allocated to the facilities.
Customer name field (optional) - the values in this field are used to identify the facilities. If the field is not specified the FID will be used as a name
Number of facilities to be selected.
Cutoff distance (optional) - the maximum distance between a Facility and a Customer to be used. Note that some customers might not be allocated if too small cutoff distance is used.

Outputs:

New Point layer containing only the selected facilities. The attribute table of the resulting feature class will have the following fields
- FacilityID - The original FID of the selected facility
- Facility - The value in the user specified Name field of the selected facility
- Type - the type of the facility - Selected or Fixed (if the facility was indicated as fixed in the input facilities dataset.
- Num_Alloc - Number of customers allocated to this facility
- Max_Dist - The distance to the farthest customer from this facility.
- Total_Dist - The sum of the distances to all allocated cutomers.
New Polyline feature class with lineslinking selected facilities to allocated to them customers. The attribute table of the resulting feature class will have the following fields
- FacilityID - The original FID of the selected facility
- CustomerID - The original FID of the customer
- Facility - The value in the user specified Name field of the selected facility
- Customer - The value in the user specified Name field of the customer
- ET_Dist - The distance between the selected facility and the allocated customer

Illustration:

Input Facilities and Customers - No required facilities

Input Facilities and Customers - No required facilities

Result (Selected facilities in green)

Result (Selected facilities in green)

Input Facilities and Customers - Two required facilities

I<span>nput Facilities and Customers - Two required facilities

Result (Selected facilities in green)

Result (Selected facilities in green)

Notes:

The output spatial reference will be the one of the Facilities dataset
The function has a restrictions and should not be applied if Number of Customers * Number Facilities > 5 Million

References:

M.B. Teitz and P. Bart, Heuristic methods for estimating the generalized vertex median of a weighted graph. Gpns. Res. 16,
955-961 (1968).

Running Programmatically

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Parameters

Expression	Explanation
Function Name	Allocate
<facilities dataset>	A Point layer - the candidate facilities.
<customers dataset>	A Point feature class or feature layer - the Customers (demand points).
<out link layer>	A String - the full name of the output link layer
<out facilities layer>	A String - the full name of the output selected facilities feature class
<number facilities>	An integer - the number of facilities to be selected
{facility name field}	A String representing a field name - the values in this field are used to identify the facilities.
{facility type field}	A String representing a field name - the values in this field are used to identify the type of the facilities.
{customer name field}	A String representing a field name - the values in this field are used to identify the customers.
{Cutoff distance}	A number - the maximum distance between a Facility and a Customer to be used.The units of the tolerance are the units of spatial reference of the facilities dataset if KeepSourceSref = TRUE. Otherwise - the units of spatial reference of the customers dataset.
{Keep Customers Sref}	A Boolean indicating whether the output to have the spatial reference of the customers layer. If False or 0, the spatial reference of the facilities layer will be used.

Running the function

ETGWPath used in the table below is the full path to ETGWRun.exe (E.G. "C:\Program Files\ETSpatial Techniques\ETGeo Wizards\ETGWRun.exe")

Language	Syntax
Python	subprocess.call([ETGWPath, "Allocate", "facilities dataset", "customers dataset", "out link layer", " out facilities layer", "number facilities", "facility name field", "facility type field","customer name field","Cutoff distance ","KeepSourceSref"])
.NET using ETGWRun.exe	StartInfo.FileName = ETGWPath StartInfo.Arguments = "Allocate" "facilities dataset" "customers dataset" "out link layer" "out facilities layer" "number facilities" "facility name field" "facility type field" "customer name field" "Cutoff distance " "KeepSourceSref"
.NET using ETGWOutX.dll	Allocate(facilities dataset,customers dataset, out link layer,out facilities layer, number facilities, facility name field, facility type field, customer name field, Cutoff distance KeepSourceSref)
ArcPy	arcpy.Allocate(facilities dataset,customers dataset, out link layer,out facilities layer, number facilities, facility name field, facility type field, customer name field, Cutoff distance KeepSourceSref)

Notes:

<> - required parameter
{} - optional parameter
See examples for Python , .NET or ArcPy
The argument separator for StartInfo.Arguments is space. If a string might contain a space, you need to double quote it.

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