set_num_edges Module Subroutine

  module subroutine set_num_edges(this, num_edges, num_edge_features)
    !! Set the number of edges of the graph.
    !!
    !! This will deallocate the existing edges and set the number of edges.
    !! New edges will be allocated but not initialised.
    implicit none

    ! Arguments
    class(graph_type), intent(inout) :: this
    !! Parent. Instance of the graph structure.
    integer, intent(in) :: num_edges
    !! Number of edges in the graph.
    integer, intent(in), optional :: num_edge_features
    !! Number of edge features.

    ! Deallocate existing data
    if(allocated(this%edge)) deallocate(this%edge)
    if(allocated(this%adj_ia)) deallocate(this%adj_ia)
    if(allocated(this%adj_ja)) deallocate(this%adj_ja)
    if(allocated(this%adjacency)) deallocate(this%adjacency)
    
    ! Set new dimensions
    this%num_edges = num_edges
    if(present(num_edge_features)) this%num_edge_features = num_edge_features
    
    ! Allocate appropriate storage
    if(this%is_sparse)then
       allocate(this%edge_features(this%num_edge_features, this%num_edges))
       allocate(this%edge_weights(this%num_edges))
    else
       allocate(this%edge(num_edges))
    end if

  end subroutine set_num_edges