Scanpy on Biowulf
Scanpy is a scalable toolkit for analyzing single-cell gene expression data. It includes preprocessing, visualization, clustering, pseudotime and trajectory inference and differential expression testing. The Python-based implementation efficiently deals with datasets of more than one million cells.
References:
- Wolf FA, Angerer P, Theis FJ. SCANPY: large-scale single-cell gene expression data analysis. Genome Biol. 2018 Feb 6;19(1):15.
Documentation
Important Notes
- Module Name: scanpy (see the modules page for more information)
- Multithreaded/singlethreaded
- Example files in $SCANPY_EXAMPLES
This application contains graphical content and requires an X-Windows connection.
Interactive job
Interactive jobs should be used for debugging, graphics, or applications that cannot be run as batch jobs.
Allocate an interactive session and run the program.
Sample session (user input in bold):
[user@biowulf]$ sinteractive salloc.exe: Pending job allocation 46116226 salloc.exe: job 46116226 queued and waiting for resources salloc.exe: job 46116226 has been allocated resources salloc.exe: Granted job allocation 46116226 salloc.exe: Waiting for resource configuration salloc.exe: Nodes cn0860 are ready for job [user@cn0860 ~]$ module load scanpy [+] Loading scanpy 1.8.1 on cn0860 [+] Loading singularity 3.8.2 on cn0860 [user@cn0860 ~]$ cp -r $SCANPY_DATA/* . [user@cn0860 ~]$ python-scanpy cluster.py scanpy==1.8.1 anndata==0.7.6 umap==0.5.1 numpy==1.20.3 scipy==1.7.1 pandas==1.3.2 scikit-learn==0.24.2 statsmodels==0.12.2 python-igraph==0.9.6 pynndescent==0.5.4 ... reading from cache file cache/data-filtered_gene_bc_matrices-hg19-matrix.h5ad normalizing counts per cell finished (0:00:00)

filtered out 19024 genes that are detected in less than 3 cells



/Miniconda/lib/python3.9/site-packages/scanpy/preprocessing/_normalization.py:155: UserWarning: Revieved a view of an AnnData. Making a copy. view_to_actual(adata) normalizing counts per cell finished (0:00:00) extracting highly variable genes finished (0:00:00)

/Miniconda/lib/python3.9/site-packages/scanpy/preprocessing/_simple.py:373: UserWarning: Revieved a view of an AnnData. Making a copy. view_to_actual(adata) regressing out ['total_counts', 'pct_counts_mt'] sparse input is densified and may lead to high memory use finished (0:00:10)
[user@cn0860 ~]$ exit salloc.exe: Relinquishing job allocation 46116226 [user@biowulf ~]$
Batch job
Most jobs should be run as batch jobs.
Create a batch input file (e.g. scanpy.sh). For example:
#!/bin/bash module load scanpy python-scanpy my_script.py
Submit this job using the Slurm sbatch command.
sbatch [--cpus-per-task=#] [--mem=#] scanpy.sh