1 Introduction

1.1 Motivation

The spatialHeatmap package provides functionalities for visualizing cell-, tissue- and organ-specific data of biological assays by coloring the corresponding spatial features defined in anatomical images according to quantitative abundance levels of measured biomolecules, such as transcripts, proteins or metabolites. A color key is used to represent the quantitative assay values and can be customized by the user. This core functionality of the package is called a spatial heatmap (SHM) plot. Additional important functionalities include Spatial Enrichment (SE), Spatial Co-Expression (SCE), and Single Cell to SHM Co-Visualization (SC2SHM-CoViz). These extra utilities are useful for identifying biomolecules with spatially selective abundance patterns (SE), groups of biomolecules with related abundance profiles using hierarchical clustering, K-means clustering, or network analysis (SCE), and to co-visualize single cell embedding results with SHMs (SCSHM-CoViz). The latter co-visualization functionality (Figure 1E) is described in a separate vignette called SCSHM-CoViz.

The functionalities of spatialHeatmap can be used either in a command-driven mode from within R or a graphical user interface (GUI) provided by a Shiny App that is part of this project. While the R-based mode provides flexibility to customize and automate analysis routines, the Shiny App includes a variety of convenience features that will appeal to experimentalists and users less familiar with R. The Shiny App can be used on both local computers as well as centralized server-based deployments (e.g. cloud-based or custom servers). This way it can be used for both hosting community data on a public server or running on a private system. The core functionalities of the spatialHeatmap package are illustrated in Figure 1.