Fig. 1. Overview of SpaceFlow.
a The input ST dataset consist of an expression count matrix and spatial coordinates of spots/cells. b A spatial expression graph (SEG) is constructed as the network input, with edges characterizing the spatial neighborhood, and nodes representing cells/spots with expression profiles attached. By randomly permuting the nodes in SEG, Expression Permuted Graphs (EPG) are built as negative samples. c A two-layer GCN encodes the SEG or EPG input into low-dimensional embeddings. d The embeddings are regularized for spatial consistency. With the Spatial Regularization loss and the Discriminator loss, the encoder is iteratively trained until convergence. e The low-dimensional embedding is obtained from the trained encoder. f The output consists of the pseudo-Spatiotemporal Map (pSM), domain segmentation, and the visualization of low-dimensional embeddings.