graphembed 0.0.8

graph embedding
Documentation 
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//! Graph can come with many types of discrete labels. We need to map original labels of graph data files to discrete labels.
//!
//! It is possible to have labels in datafile that can be mapped to our discrete labels but that
//! are neither strings nor u6, u16 etc.  
//! Moreover the default initialization of labels (i.E 0 for u8, u16 etc)
//! is used internally to cover the case where a  node has no input (or output) edge. In this case
//! the embedded vector is represented by the default value (i.e 0).
//! **So effective labels stored in the graph must not be 0!!**
//!
//! We must also store reordering of nodes.
//!

use std::hash::Hash;

use petgraph::stable_graph::NodeIndex;

use indexmap::IndexMap;

use super::pgraph::*;

// TODO Do we keep u32 or do we parametrize on initial node Id?

/// ToLabel is the original label of nodes (or edge) of graph, Label is discrete label associated to Nodes in MgraphSketch
pub struct IdMap<ToLabel, Label>
where
    Label: LabelT,
    ToLabel: Eq + Hash,
{
    /// given a node rank in file get the NodeIndex in graph
    ranktoidx: IndexMap<u32, NodeIndex>,
    /// given the original label, get the discrete label used in node labeling
    relabel: IndexMap<ToLabel, Label>,
} // end of struct IdMap

/// When loading a datafile, A graph is returned together with a structure satisfying trait IdMapper
///
/// When a node has no input edge or no output edge, if we want to get an Array2 are embedding result we must define a specific label
/// to fill the corresponding In or Out sketching vector. This is the Default label!
/// (An alternative woud have been to return an Option\<Vec\> for each node, but still we would have to relabel to fit into our labels)
/// Moreover we may need to map labels in datafile to out implemented labels. So there is a specific relabelling pass in reading data
/// Typically the default label 0 must be remapped to someting else (max label used + 1)
/// In the same way at the end of the embedding process we do have correspondance between embedded vectors (accessed by a row in embbed Array2 corresponding
/// to a NodeIndex) and initial rank of node
///
pub trait IdMapper<ToLabel, Label> {
    fn get_nodeindex(&self, rank: u32) -> Option<&NodeIndex>;
    //
    fn get_label(&self, oldlabel: ToLabel) -> Option<&Label>;
} // end of trait IdMapper

impl<ToLabel, Label> IdMap<ToLabel, Label>
where
    Label: LabelT,
    ToLabel: Eq + Hash,
{
    pub fn new(ranktoidx: IndexMap<u32, NodeIndex>, relabel: IndexMap<ToLabel, Label>) -> Self {
        IdMap { ranktoidx, relabel }
    }
} // end of impl IdMap

impl<ToLabel, Label> IdMapper<ToLabel, Label> for IdMap<ToLabel, Label>
where
    Label: LabelT,
    ToLabel: Eq + Hash,
{
    /// get NodeIndex from rank in datafile
    fn get_nodeindex(&self, rank: u32) -> Option<&NodeIndex> {
        self.ranktoidx.get(&rank)
    } // end of get_nodeindex

    /// get new label from initial label in data file
    fn get_label(&self, oldlabel: ToLabel) -> Option<&Label> {
        self.relabel.get(&oldlabel)
    } // end of get_label
} // end of impl block