Before using code patterns, verify installed versions match. If versions differ:
Python: pip show <package> then help(module.function) to check signatures
If code throws ImportError, AttributeError, or TypeError, introspect the installed
package and adapt the example to match the actual API rather than retrying.
Cell Phenotyping for IMC
"Assign cell types to my segmented IMC cells" → Classify cells based on protein marker expression using clustering, manual gating, or supervised classification approaches.
Python: scanpy.tl.leiden() for unsupervised clustering, then manual annotation
R: FlowSOM for self-organizing map-based phenotyping
Load Single-Cell Data
import anndata as ad
import scanpy as sc
import pandas as pd
import numpy as np
# Load from h5ad
adata = ad.read_h5ad('imc_segmented.h5ad')
# Or create from CSVs
intensities = pd.read_csv('cell_intensities.csv')
cell_info = pd.read_csv('cell_info.csv')
adata = ad.AnnData(X=intensities.values)
adata.var_names = intensities.columns
adata.obs = cell_info
def gate_cells(adata, marker, threshold, above=True):
'''Gate cells based on marker expression'''
values = adata[:, marker].X.flatten()
if above:
return values > threshold
else:
return values < threshold
# Example gating strategy for T cells
adata.obs['CD45_pos'] = gate_cells(adata, 'CD45', 1.5)
adata.obs['CD3_pos'] = gate_cells(adata, 'CD3', 1.0)
adata.obs['CD8_pos'] = gate_cells(adata, 'CD8', 0.8)
adata.obs['CD4_pos'] = gate_cells(adata, 'CD4', 0.8)
# Assign cell types
def assign_cell_type(row):
if not row['CD45_pos']:
return 'Other'
if not row['CD3_pos']:
return 'Non-T immune'
if row['CD8_pos']:
return 'CD8 T cell'
if row['CD4_pos']:
return 'CD4 T cell'
return 'T cell (other)'
adata.obs['cell_type'] = adata.obs.apply(assign_cell_type, axis=1)
Cluster Annotation
# Find marker genes per cluster
sc.tl.rank_genes_groups(adata, 'leiden', method='wilcoxon')
sc.pl.rank_genes_groups_heatmap(adata, n_genes=5, save='_markers.png')
# Manual annotation based on markers
cluster_annotation = {
'0': 'Epithelial',
'1': 'CD8 T cell',
'2': 'CD4 T cell',
'3': 'Macrophage',
'4': 'Stromal',
'5': 'B cell'
}
adata.obs['cell_type'] = adata.obs['leiden'].map(cluster_annotation)
SOM-Based Clustering (FlowSOM-Style)
Goal: Cluster cells into phenotypically distinct populations using a self-organizing map approach analogous to the FlowSOM algorithm used in flow cytometry.
Approach: Train a self-organizing map on selected phenotype markers, map each cell to its best-matching unit, then apply agglomerative meta-clustering on the SOM node weights to obtain final cell type clusters.
# FlowSOM-style clustering using minisom
# Note: For authentic FlowSOM, use the R CATALYST package which wraps FlowSOM
# This Python approach approximates the SOM + meta-clustering concept
from minisom import MiniSom
from sklearn.cluster import AgglomerativeClustering
# Markers for clustering
phenotype_markers = ['CD45', 'CD3', 'CD8', 'CD4', 'CD20', 'CD68', 'E-cadherin']
X = adata[:, phenotype_markers].X
# Self-Organizing Map
som = MiniSom(10, 10, X.shape[1], sigma=1.5, learning_rate=0.5)
som.random_weights_init(X)
som.train_random(X, 1000)
# Get cluster assignments
winner_coordinates = np.array([som.winner(x) for x in X])
som_clusters = winner_coordinates[:, 0] * 10 + winner_coordinates[:, 1]
# Meta-clustering
meta_clustering = AgglomerativeClustering(n_clusters=10)
meta_labels = meta_clustering.fit_predict(som.get_weights().reshape(-1, X.shape[1]))
# Assign to cells
adata.obs['som_cluster'] = [meta_labels[c] for c in som_clusters]
Automated Annotation
# Use reference-based annotation (similar to CellTypist)
from sklearn.neighbors import KNeighborsClassifier
# If you have a reference dataset with known labels
ref_data = ad.read_h5ad('reference_imc.h5ad')
# Train classifier
knn = KNeighborsClassifier(n_neighbors=15)
knn.fit(ref_data.X, ref_data.obs['cell_type'])
# Predict
adata.obs['predicted_type'] = knn.predict(adata.X)
adata.obs['prediction_prob'] = knn.predict_proba(adata.X).max(axis=1)
Visualize Phenotypes
import matplotlib.pyplot as plt
# UMAP colored by cell type
sc.pl.umap(adata, color='cell_type', save='_celltypes.png')
# Heatmap of markers by cell type
sc.pl.matrixplot(adata, phenotype_markers, groupby='cell_type',
dendrogram=True, cmap='RdBu_r', save='_heatmap.png')
# Spatial plot colored by cell type
fig, ax = plt.subplots(figsize=(10, 10))
spatial = adata.obsm['spatial']
for ct in adata.obs['cell_type'].unique():
mask = adata.obs['cell_type'] == ct
ax.scatter(spatial[mask, 0], spatial[mask, 1], s=1, label=ct, alpha=0.7)
ax.legend(markerscale=5)
ax.set_aspect('equal')
plt.savefig('spatial_celltypes.png', dpi=150)
