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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 feature class 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 lines linking 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	Result (Selected facilities in green)
Input Facilities and Customers - Two required facilities	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).