Ensemble Learning for Harmonization and Annotation of Single Cells (ELeFHAnt) provides an easy to use R package for users to annotate clusters of single cells, harmonize labels across single cell datasets to generate a unified atlas and infer relationship among celltypes between two datasets. It uses ensemble of randomForest (RF), Support Vector Machines (SVM) and Logistic Regression (LR). It has Six main functions 1) CelltypeAnnotation 2) LabelHarmonization 3) DeduceRelationship 4) Benchmark ELeFHAnt 5) CrossSpecies Conversion and 6) Validate Predictions

• Uses three classifiers to form an ensemble to classify cells [RF, SVM and LR].
• Improved speed (5X faster classification)
• Validate Predictions using GSEA msigdb [C8] (https://www.gsea-msigdb.org/gsea/msigdb/collections.jsp#C8) and CellMarkers Database markers (http://bio-bigdata.hrbmu.edu.cn/CellMarker/) [Experimental Markers]
• Users can select species (human or mouse) and tissues of interest for predicted celltype Marker validation. [Dotplots and Feature plots are generated for query/integrated data]
• Users now can compare ELeFHAnt predictions against Seurat's Label Transfer and scPred by using BenchmarkELeFHAnt function
• A complete tutorial using PBMC datasets is provided. Reference [https://www.nature.com/articles/ncomms14049] and query [https://cf.10xgenomics.com/samples/cell/pbmc3k/pbmc3k_filtered_gene_bc_matrices.tar.gz]

Users can access ELeFHAnt previous releases from Releases section of GitHub [https://github.com/praneet1988/ELeFHAnt/releases]

library(devtools)
devtools::install_github('praneet1988/ELeFHAnt')
library(ELeFHAnt)

If you encounter any problems, try manually installing from the .zip or .tar.gz file with "R CMD INSTALL". 

https://rpubs.com/praneet1988/ELeFHAnt

Random Forests is a powerful tool used extensively across a multitude of fields. It is based on generating a large number of decision trees, each constructed using a different subset of your training set. These subsets are usually selected by sampling at random and with replacement from the original data set. The decision trees are then used to identify a classification consensus by selecting the most common output.

SVM is a well-established supervised machine learning algorithm. It finds a hyperplane that separates data points into classes, where training occurs through “maximizing the margin”. Training time tends to be longer as data increases. SVM was ranked highly for cell annotation when benchmarked against other tools.

Logistic regression estimates the probability of an event occurring, such as voted or didn't vote, based on a given dataset of independent variables. Since the outcome is a probability, the dependent variable is bounded between 0 and 1

ELeFHAnt provides users the ability to use ensemble learning for classification using three classifiers.

Celltype annotation is a function used to annotate celltypes in single cell datasets. It requires a reference dataset (a processed Seurat Object) and a query dataset (a processed seurat object with seurat_clusters column in metadata).

Label Harmonization is a function used to harmonize cell labels (celltypes) across single cell datasets. It requires a list of processed Seurat Objects or an integrated seurat object.

Deduce Relationship is a function used to infer the relative similarity between metadata of interest (MOI) across single cell datasets. The output is a heatmap that shows how MOI in one reference best corresponds to MOI in another reference. It requires two reference datasets (both processed Seurat Objects).

Benchmark ELeFHAnt is a function to compare ELeFHAnt celltype predictions against scPred and Seurat's Label Transfer.

CrossSpecies Conversion takes one or more datasets and maps their genes to orthologs in other species. The datasets are updated with the new gene names, ensuring they have the same set of features prior to using the other functions. This enables users to, for example, use a mouse reference to annotate a human query. Human, mouse, rat, rhesus, chicken, and zebrafish options are provided. It can also convert between ensembl gene ids and gene symbol formats.

This function uses the package biomaRt to map genes to one other, and therefore requires an internet connection. Please note that some genes may not map to anything, and for one-to-many or many-to-one mappings only the first is kept and the rest are ignored. Any genes without matches will be removed, and the dataset is then reprocessed in Seurat. Finally, this function only operates on the RNA assay, so please perform prior to integration.

Praneet Chaturvedi (MS Bioinformatics) : Lead Analyst Bioinformatics, Cincinnati Children's Hospital and Medical Center, Cincinnati, OH - USA
GitHub Username: praneet1988

Konrad Thorner (MS Bioinformatics) : Analyst Bioinformatics, Cincinnati Children's Hospital and Medical Center, OH - USA
GitHub Username: kthorner

Please cite our preprint: https://www.biorxiv.org/content/10.1101/2021.09.07.459342v1 when using ELeFHAnt in your research.

Please report bugs, issues and improvements using the issues section of the GitHub page.

Please open a pull request to contribute to existing code in terms of improvements / new features / bug removal.