A method for grouping a plurality of orders in an order queue (650, 820) of a warehouse management system, each order including one or more items (673, 675, 821a-d) and each item being associated with a physical location in a warehouse (10, 600), the method comprising: retrieving, by a processor from a data structure, two dimensional coordinates (x, y) (654, 656, 658) of each of the items in the plurality of orders in a coordinate space defined by the warehouse (10, 600) associated with the physical location in the warehouse (10, 600) of each item in the plurality of orders; forming, by the processor for each order of the plurality of orders, at least one cluster region (614, 616, 618, 672, 674) defined by a radius, R, about the two dimensional coordinates (x,y) of at least one item (673, 675, 821a-d) from a respective order of the plurality of orders; wherein the step of forming includes, for each item (673, 675, 821a-d) in each of the plurality of orders, determining if the two dimensional coordinates (x,y) are contained within an already established cluster region (614, 616, 618, 672, 674) for the order and, if they are, assigning each such item to the respective cluster region for the order; and, if they are not contained within an already established cluster region, establishing a new cluster region about the two dimensional coordinates (x, y) for each such item in the respective order; calculating, by the processor, for each order a physical location for each cluster region and comparing the physical location of each cluster region in an order to the location of a corresponding cluster region from at least one other of the plurality of orders; grouping, by the processor, the plurality of orders based on the physical locations of the cluster regions (614, 616, 618, 672, 674) in the warehouse (10, 600) to form at least one order set to be picked; assigning, by the processor, the at least one order set to one of a human operator or an autonomous mobile robot by electronically transmitting the at least one order set to be picked to one of a handheld electronic device for the human operator or an onboard electronic device for the autonomous mobile robot; and wherein the step of calculating the physical location of each cluster region is determined by calculating an average of the two dimensional coordinates (x, y) of each item in the respective cluster region to obtain a midpoint location for each of the cluster regions and wherein the midpoint location is used as the physical location of each of the cluster regions. retrieving, by a processor from a data structure, two dimensional coordinates (x, y) (654, 656, 658) of each of the items in the plurality of orders in a coordinate space defined by the warehouse (10, 600) associated with the physical location in the warehouse (10, 600) of each item in the plurality of orders; forming, by the processor for each order of the plurality of orders, at least one cluster region (614, 616, 618, 672, 674) defined by a radius, R, about the two dimensional coordinates (x,y) of at least one item (673, 675, 821a-d) from a respective order of the plurality of orders; wherein the step of forming includes, for each item (673, 675, 821a-d) in each of the plurality of orders, determining if the two dimensional coordinates (x,y) are contained within an already established cluster region (614, 616, 618, 672, 674) for the order and, if they are, assigning each such item to the respective cluster region for the order; and, if they are not contained within an already established cluster region, establishing a new cluster region about the two dimensional coordinates (x, y) for each such item in the respective order; calculating, by the processor, for each order a physical location for each cluster region and comparing the physical location of each cluster region in an order to the location of a corresponding cluster region from at least one other of the plurality of orders; grouping, by the processor, the plurality of orders based on the physical locations of the cluster regions (614, 616, 618, 672, 674) in the warehouse (10, 600) to form at least one order set to be picked; assigning, by the processor, the at least one order set to one of a human operator or an autonomous mobile robot by electronically transmitting the at least one order set to be picked to one of a handheld electronic device for the human operator or an onboard electronic device for the autonomous mobile robot; and wherein the step of calculating the physical location of each cluster region is determined by calculating an average of the two dimensional coordinates (x, y) of each item in the respective cluster region to obtain a midpoint location for each of the cluster regions and wherein the midpoint location is used as the physical location of each of the cluster regions.