Preclustering and Cluster Enriched Features

Contents

Preclustering and Cluster Enriched Features¶

Purpose¶

The purpose of this step is to perform a simple pre-clustering using the highly variable features to get a pre-clusters labeling. We then select top enriched features for each cluster (CEF) for further analysis.

Input¶

HVF adata file.

Output¶

HVF adata file with pre-clusters and CEF annotated.

Import¶

import seaborn as sns
import anndata
import scanpy as sc
from ALLCools.clustering import cluster_enriched_features, significant_pc_test, log_scale

sns.set_context(context='notebook', font_scale=1.3)

Parameters¶

adata_path = 'mCH.HVF.h5ad'

# Cluster Enriched Features analysis
top_n=200
alpha=0.05
stat_plot=True

# you may provide a pre calculated cluster version. 
# If None, will perform basic clustering using parameters below.
cluster_col = None  

# These parameters only used when cluster_col is None
k=25
resolution=1
cluster_plot=True

Load Data¶

adata = anndata.read_h5ad(adata_path)

Pre-Clustering¶

If cluster label is not provided, will perform basic clustering here

if cluster_col is None:
    # IMPORTANT
    # put the unscaled matrix in adata.raw
    adata.raw = adata
    log_scale(adata)
    
    sc.tl.pca(adata, n_comps=100)
    significant_pc_test(adata, p_cutoff=0.1, update=True)
    
    sc.pp.neighbors(adata, n_neighbors=k)
    sc.tl.leiden(adata, resolution=resolution)
    
    if cluster_plot:
        sc.tl.umap(adata)
        sc.pl.umap(adata, color='leiden')
    
    # return to unscaled X, CEF need to use the unscaled matrix
    adata = adata.raw.to_adata()
    
    cluster_col = 'leiden'

../../../_images/04a-PreclusteringAndClusterEnrichedFeatures-mCH_9_0.png

Cluster Enriched Features (CEF)¶

cluster_enriched_features(adata,
                          cluster_col=cluster_col,
                          top_n=top_n,
                          alpha=alpha,
                          stat_plot=True)

Found 31 clusters to compute feature enrichment score
Computing enrichment score
Computing enrichment score FDR-corrected P values
Selected 3228 unique features

../../../_images/04a-PreclusteringAndClusterEnrichedFeatures-mCH_11_1.png

Save AnnData¶

# save adata
adata.write_h5ad(adata_path)
adata

AnnData object with n_obs × n_vars = 16985 × 20000
    obs: 'leiden'
    var: 'bin_end', 'bin_start', 'chrom', 'CHN_mean', 'CHN_dispersion', 'CHN_cov', 'CHN_score', 'CHN_feature_select', 'leiden_enriched_features'
    uns: 'log', 'pca', 'neighbors', 'leiden', 'umap', 'leiden_colors', 'leiden_feature_enrichment'
    obsm: 'X_pca', 'X_umap'

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