From a43b5a2e5355ee4fcd0cb09e3a14d36f03a2304a Mon Sep 17 00:00:00 2001
From: Zhong Hui <zhonghui.net@gmail.com>
Date: Wed, 1 Jul 2020 18:10:07 +0800
Subject: [PATCH] add graphsaint

---
 pgl/graph_kernel.pyx | 40 ++++++++++++++++++++++++++++++++
 pgl/sample.py        | 55 ++++++++++++++++++++++++++++++++++++--------
 2 files changed, 85 insertions(+), 10 deletions(-)

diff --git a/pgl/graph_kernel.pyx b/pgl/graph_kernel.pyx
index 5e5f289..52ad265 100644
--- a/pgl/graph_kernel.pyx
+++ b/pgl/graph_kernel.pyx
@@ -321,3 +321,43 @@ def alias_sample_build_table(np.ndarray[np.float64_t, ndim=1] probs):
             if alias[l_i] < 1:
                 smaller_num.push_back(l_i)
     return alias, events
+
+
+@cython.boundscheck(False)
+@cython.wraparound(False)
+def adj_extract(
+    np.ndarray[np.int64_t, ndim=1] adj_indptr,
+    np.ndarray[np.int64_t, ndim=1] sorted_v,
+    vector[long long] sampled_nodes,
+):
+    """
+    Extract all eids of given sampled_nodes for the origin graph.
+    ret_edge_index: edge ids between sampled_nodes.
+
+    Refers: https://github.com/GraphSAINT/GraphSAINT
+    """
+    cdef long long i, v, j
+    cdef long long num_v_orig, num_v_sub
+    cdef long long start_neigh, end_neigh
+    cdef vector[int] _arr_bit
+    cdef vector[long long] ret_edge_index
+    num_v_orig = adj_indptr.size-1
+    _arr_bit = vector[int](num_v_orig,-1)
+    num_v_sub = sampled_nodes.size()
+    i = 0
+    with nogil:
+        while i < num_v_sub:
+            _arr_bit[sampled_nodes[i]] = i
+            i = i + 1
+        i = 0
+        while i < num_v_sub:
+            v = sampled_nodes[i]
+            start_neigh = adj_indptr[v]
+            end_neigh = adj_indptr[v+1]
+            j = start_neigh
+            while j < end_neigh:
+                if _arr_bit[sorted_v[j]] > -1:
+                    ret_edge_index.push_back(j)
+                j = j + 1
+            i = i + 1
+    return ret_edge_index
diff --git a/pgl/sample.py b/pgl/sample.py
index 89c1d1b..c7b2a31 100644
--- a/pgl/sample.py
+++ b/pgl/sample.py
@@ -55,7 +55,7 @@ def edge_hash(src, dst):
 
 def graphsage_sample(graph, nodes, samples, ignore_edges=[]):
     """Implement of graphsage sample.
-    
+
     Reference paper: https://cs.stanford.edu/people/jure/pubs/graphsage-nips17.pdf.
 
     Args:
@@ -63,7 +63,7 @@ def graphsage_sample(graph, nodes, samples, ignore_edges=[]):
         nodes: Sample starting from nodes
         samples: A list, number of neighbors in each layer
         ignore_edges: list of edge(src, dst) will be ignored.
-    
+
     Return:
         A list of subgraphs
     """
@@ -129,7 +129,7 @@ def alias_sample(size, alias, events):
         size: Output shape.
         alias: The alias table build by `alias_sample_build_table`.
         events: The events table build by `alias_sample_build_table`.
-    
+
     Return:
         samples: The generated random samples.
     """
@@ -283,13 +283,13 @@ def metapath_randomwalk(graph,
     Args:
         graph: instance of pgl heterogeneous graph
         start_nodes: start nodes to generate walk
-        metapath: meta path for sample nodes. 
+        metapath: meta path for sample nodes.
             e.g: "c2p-p2a-a2p-p2c"
         walk_length: the walk length
 
     Return:
-        a list of metapath walks. 
-        
+        a list of metapath walks.
+
     """
 
     edge_types = metapath.split('-')
@@ -390,18 +390,18 @@ def pinsage_sample(graph,
                    norm_bais=1.0,
                    ignore_edges=set()):
     """Implement of graphsage sample.
-    
+
     Reference paper: .
 
     Args:
         graph: A pgl graph instance
         nodes: Sample starting from nodes
         samples: A list, number of neighbors in each layer
-        top_k: select the top_k visit count nodes to construct the edges 
-        proba: the probability to return the origin node 
+        top_k: select the top_k visit count nodes to construct the edges
+        proba: the probability to return the origin node
         norm_bais: the normlization for the visit count
         ignore_edges: list of edge(src, dst) will be ignored.
-    
+
     Return:
         A list of subgraphs
     """
@@ -476,3 +476,38 @@ def pinsage_sample(graph,
             layer_nodes[0], dtype="int64")
 
     return subgraphs
+
+
+def graph_saint_random_walk_sample(graph,
+                                   nodes,
+                                   max_depth,
+                                   alias_name=None,
+                                   events_name=None):
+    """Implement of graph saint random walk sample.
+
+    First, this function will get random walks path for given nodes and depth.
+    Then, it will create subgraph from all sampled nodes.
+
+    Reference Paper: https://arxiv.org/abs/1907.04931
+
+    Args:
+        graph: A pgl graph instance
+        nodes: Walk starting from nodes
+        max_depth: Max walking depth
+
+    Return:
+        a subgraph of sampled nodes.
+    """
+    graph.indegree()
+    walks = deepwalk_sample(graph, nodes, max_depth, alias_name, events_name)
+    sample_nodes = []
+    for walk in walks:
+        sample_nodes.extend(walk)
+    sample_nodes = np.unique(sample_nodes)
+    eids = graph_kernel.adj_extract(graph._adj_dst_index._indptr,
+                                    graph._adj_dst_index._sorted_v,
+                                    sample_nodes)
+    subgraph = graph.subgraph(
+        nodes=sample_nodes, eid=eids, with_node_feat=True, with_edge_feat=True)
+    subgraph.node_feat["index"] = np.array(sample_nodes, dtype="int64")
+    return subgraph
-- 
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