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Version Compatibility
Reference examples tested with: MetaPhlAn 4.1+, ggplot2 3.5+, matplotlib 3.8+, pandas 2.2+, phyloseq 1.46+, scanpy 1.10+, scikit-learn 1.4+, scipy 1.12+, seaborn 0.13+, vegan 2.6+
Before using code patterns, verify installed versions match. If versions differ:
Python: pip show <package> then help(module.function) to check signatures
R: packageVersion('<pkg>') then ?function_name to verify parameters
CLI: <tool> --version then <tool> --help to confirm flags
If code throws ImportError, AttributeError, or TypeError, introspect the installed
package and adapt the example to match the actual API rather than retrying.
Metagenome Visualization
"Visualize the taxonomic composition of my metagenomes" → Create publication-quality figures (stacked bars, heatmaps, ordination plots) from taxonomic profiling output to compare community composition across samples.
R: phyloseq::plot_bar(), microbiome package
Python: matplotlib/seaborn with pandas for custom compositions
Python - Stacked Bar Plot
import pandas as pd
import matplotlib.pyplot as plt
abundance = pd.read_csv('merged_abundance.txt', sep='\t', index_col=0)
abundance = abundance[abundance.index.str.contains('s__')]
abundance.index = abundance.index.str.split('|').str[-1].str.replace('s__', '')
top_n = 10
top_species = abundance.sum(axis=1).nlargest(top_n).index
abundance_top = abundance.loc[top_species]
abundance_top.loc['Other'] = abundance.drop(top_species).sum()
abundance_top.T.plot(kind='bar', stacked=True, figsize=(12, 6), colormap='tab20')
plt.xlabel('Sample')
plt.ylabel('Relative Abundance (%)')
plt.title('Species Composition')
plt.legend(bbox_to_anchor=(1.02, 1), loc='upper left')
plt.tight_layout()
plt.savefig('stacked_bar.png', dpi=300)
Python - Heatmap
import pandas as pd
import seaborn as sns
import matplotlib.pyplot as plt
abundance = pd.read_csv('merged_abundance.txt', sep='\t', index_col=0)
abundance = abundance[abundance.index.str.contains('s__')]
abundance.index = abundance.index.str.split('|').str[-1].str.replace('s__', '')
top_species = abundance.sum(axis=1).nlargest(20).index
abundance_top = abundance.loc[top_species]
plt.figure(figsize=(12, 10))
sns.heatmap(abundance_top, cmap='YlOrRd', annot=False, cbar_kws={'label': 'Abundance (%)'})
plt.xlabel('Sample')
plt.ylabel('Species')
plt.title('Species Abundance Heatmap')
plt.tight_layout()
plt.savefig('heatmap.png', dpi=300)
Python - PCA import pandas as pd
import matplotlib.pyplot as plt
from sklearn.decomposition import PCA
from sklearn.preprocessing import StandardScaler
abundance = pd.read_csv('merged_abundance.txt', sep='\t', index_col=0).T
scaler = StandardScaler()
abundance_scaled = scaler.fit_transform(abundance)
pca = PCA(n_components=2)
pca_result = pca.fit_transform(abundance_scaled)
plt.figure(figsize=(8, 6))
plt.scatter(pca_result[:, 0], pca_result[:, 1])
for i, sample in enumerate(abundance.index):
plt.annotate(sample, (pca_result[i, 0], pca_result[i, 1]))
plt.xlabel(f'PC1 ({pca.explained_variance_ratio_[0]*100:.1f}%)')
plt.ylabel(f'PC2 ({pca.explained_variance_ratio_[1]*100:.1f}%)')
plt.title('PCA of Sample Composition')
plt.savefig('pca.png', dpi=300)
R - phyloseq Setup Goal: Convert a MetaPhlAn merged abundance table into a phyloseq object for ecological analysis and visualization in R.
Approach: Filter to species-level rows, clean taxonomy names, build an OTU table and sample metadata data frame, and assemble into a phyloseq object.
library(phyloseq)
library(ggplot2)
library(vegan)
# From MetaPhlAn merged table
abundance <- read.table('merged_abundance.txt', sep = '\t', header = TRUE, row.names = 1)
# Filter to species level
species <- abundance[grepl('s__', rownames(abundance)), ]
rownames(species) <- sapply(strsplit(rownames(species), '\\|'), tail, 1)
rownames(species) <- gsub('s__', '', rownames(species))
# Create phyloseq object
otu <- otu_table(as.matrix(species), taxa_are_rows = TRUE)
# Sample metadata (create or load)
sample_data <- data.frame(
Sample = colnames(species),
Group = c('Control', 'Control', 'Treatment', 'Treatment'),
row.names = colnames(species)
)
samp <- sample_data(sample_data)
ps <- phyloseq(otu, samp)
R - Stacked Bar Plot library(phyloseq)
library(ggplot2)
# Top taxa
top_taxa <- names(sort(taxa_sums(ps), decreasing = TRUE))[1:10]
ps_top <- prune_taxa(top_taxa, ps)
# Stacked bar
plot_bar(ps_top, fill = 'Species') +
geom_bar(stat = 'identity', position = 'stack') +
theme_minimal() +
labs(x = 'Sample', y = 'Relative Abundance (%)') +
theme(axis.text.x = element_text(angle = 45, hjust = 1))
R - Ordination (PCoA) library(phyloseq)
library(ggplot2)
# Bray-Curtis distance
ord <- ordinate(ps, method = 'PCoA', distance = 'bray')
# Plot ordination
plot_ordination(ps, ord, color = 'Group') +
geom_point(size = 4) +
stat_ellipse() +
theme_minimal() +
labs(title = 'PCoA of Sample Composition')
R - Alpha Diversity library(phyloseq)
library(ggplot2)
# Calculate diversity metrics
alpha_div <- estimate_richness(ps, measures = c('Shannon', 'Simpson', 'Observed'))
# Add metadata
alpha_div$Group <- sample_data(ps)$Group
# Plot
ggplot(alpha_div, aes(x = Group, y = Shannon, fill = Group)) +
geom_boxplot() +
geom_jitter(width = 0.1) +
theme_minimal() +
labs(title = 'Alpha Diversity by Group', y = 'Shannon Index')
R - Beta Diversity (PERMANOVA) library(vegan)
# Get abundance matrix
abundance_matrix <- as(otu_table(ps), 'matrix')
if (taxa_are_rows(ps)) abundance_matrix <- t(abundance_matrix)
# Calculate Bray-Curtis distance
dist_bc <- vegdist(abundance_matrix, method = 'bray')
# PERMANOVA
groups <- sample_data(ps)$Group
permanova <- adonis2(dist_bc ~ groups, permutations = 999)
permanova
Krona Chart # From Kraken2 report
ktImportTaxonomy -q 1 -t 5 kraken_report.txt -o krona_chart.html
# From MetaPhlAn
metaphlan2krona.py -p profile.txt -k krona_profile.txt
ktImportText krona_profile.txt -o krona_metaphlan.html
Key Packages
Python Package Purpose matplotlib General plotting seaborn Statistical visualizations scikit-learn PCA, clustering scipy Statistical tests
R Package Purpose phyloseq Microbiome data handling vegan Community ecology ggplot2 Visualization microbiome Additional analyses
Related Skills
kraken-classification - Generate input data
metaphlan-profiling - Generate input data
abundance-estimation - Process Kraken output