scs: spatial cell selector

description

scs is a program that allows for the selection of spatially annotated points within a dataset using arbitrary bounding boxes.

given a dataset as input, once selection is complete, it will generate as output a TSV file with two columns, cell and within, which specify the relevant cell identifier and if that cell is within the defined bounding boxe(s).

to compile this project, you will need to install a rust compiler, instructions for which can be found here

usage

pressing h will bring up a small help menu explaining controls.

takes two arguments: the input directory path (mandatory) and an output path (optional, will default to standard out if no path is provided)

note: it is heavily recommended to compile scs on the release profile to achieve consistent performance.

example:

cargo run --release 'input/public' 'output.tsv'

workflow demonstration

a jupyter notebook (scripts/demo.ipynb) is provided to demonstrate how to use scs within the context of a scanpy-driven analysis

input directory structure

scs expects the input directory to have the following structure:

• a top-level cells.tsv file with three columns: cell (specifying a cell identifier), x (specifying the cell's x coordinate), and y (specifying the cell's y coordinate)
• a directory called feat, which contains feature files
  • each feature file should have the name {FEATURE_NAME}.tsv (e.g. Yap1.tsv for the Yap1 feature)
  • each feature file should have two columns: cell (specifying a cell identifier) and expr (specifying the associated value of that feature for that cell)
  • any cell not present in a feature file is assumed to have a value of 0 for that feature (given feature data is often very sparse this can keep feature file size small)
• all input TSV files should contain a header line

the scripts directory contains scripts that can generate input directories for scs using common existing data formats (such as seurat)

generating an input directory from seurat objects: scripts/from_seurat.r

generates an input directory from a seurat object saved as an RDS file.

requires the Seurat, data.table, purrr packages to be installed.

arguments:

1. input RDS file path
2. desired output directory
3. centroid FOV to use for x/y coordinates (optional, defers to seurat's defaults)
4. assay to use for features (optional, defers to seurat's defaults)
5. layer to use from selected assay for features (optional, defers to seurat's defaults)

example:

Rscript 'scripts/seurat.r' 'input/so.rds' 'input/data' # uses seurat's default values for FOV, assay, and layer
Rscript 'scripts/seurat.r' 'input/so.rds' 'input/data' 'centroids.specific' 'vizgen' 'data' # specific values

generating an input directory from anndata objects: scripts/from_anndata.py

generates an input directory from an anndata object saved as an h5ad file.

note: expects spatial coordinates to be in an obsm slot, not as a set of obs columns.

requires the anndata and pandas packages to be installed.

arguments:

1. input h5ad file path
2. desired output directory
3. obsm index to use for spatial coordinates (optional, defaults to spatial)
4. layer index to use (optional, defaults to using X matrix)

example:

python 'scripts/from_anndata.py' 'input/adata.h5ad' 'input/data' # uses default values
python 'scripts/from_anndata.py' 'input/adata.h5ad' 'input/data' 'spatial_centroids' 'counts' # specific values