A Flexible Framework for Large Graph Learning

Graph Convolutional Network (GCN) has shown strong effectiveness in graph learning tasks. However, GCN faces challenges in flexibility due to the fact of requiring the full graph Laplacian available in the training phase. Moreover, with the depth of layers increases, the computational and memory cost of GCN grows explosively on account of the recursive neighborhood expansion, which leads to a limitation in processing large graphs. To tackle these issues, we take advantage of image processing in agility and present Node2Img, a flexible architecture for large-scale graph learning. Node2Img maps the nodes to "images" (i.e. grid-like data in Euclidean space) which can be the inputs of Convolutional Neural Network (CNN). Instead of leveraging the fixed whole network as a batch to train the model, Node2Img supports a more efficacious framework in practice, where the batch size can be set elastically and the data in the same batch can be calculated parallelly. Specifically, by ranking each node's influence through degree, Node2Img selects the most influential first-order as well as second-order neighbors with central node fusion information to construct the grid-like data. For further improving the efficiency of downstream tasks, a simple CNN-based neural network is employed to capture the significant information from the Euclidean grids. Additionally, the attention mechanism is implemented, which enables implicitly specifying the different weights for neighboring nodes with different influences. Extensive experiments on real graphs' transductive and inductive learning tasks demonstrate the superiority of the proposed Node2Img model against the state-of-the-art GCN-based approaches.