Agent skill
bio-phylo-tree-io
Install this agent skill to your Project
npx add-skill https://github.com/FreedomIntelligence/OpenClaw-Medical-Skills/tree/main/skills/bio-phylo-tree-io
SKILL.md
name: bio-phylo-tree-io description: Read, write, and convert phylogenetic tree files using Biopython Bio.Phylo. Use when parsing Newick, Nexus, PhyloXML, or NeXML tree formats, converting between formats, or handling multiple trees. tool_type: python primary_tool: Bio.Phylo measurable_outcome: Execute skill workflow successfully with valid output within 15 minutes. allowed-tools:
- read_file
- run_shell_command
Tree I/O
Parse, write, and convert phylogenetic tree files in various formats.
Required Import
from Bio import Phylo
from io import StringIO
Supported Formats
| Format | Extension | Description |
|---|---|---|
newick |
.nwk, .tre, .tree | Standard format with branch lengths |
nexus |
.nex, .nxs | Rich format with annotations (PAUP, MrBayes) |
phyloxml |
.xml | XML format with metadata support |
nexml |
.nexml | Modern XML format |
cdao |
.rdf | RDF format (limited use) |
Reading Trees
# Read single tree
tree = Phylo.read('tree.nwk', 'newick')
# Read multiple trees from file
trees = list(Phylo.parse('bootstrap_trees.nwk', 'newick'))
print(f'Loaded {len(trees)} trees')
# Read from string
tree_string = '((A:0.1,B:0.2):0.3,(C:0.4,D:0.5):0.6);'
tree = Phylo.read(StringIO(tree_string), 'newick')
# Read PhyloXML with metadata
tree = Phylo.read('annotated.xml', 'phyloxml')
# Read Nexus (often contains multiple trees)
trees = list(Phylo.parse('mrbayes.nex', 'nexus'))
Writing Trees
# Write single tree
Phylo.write(tree, 'output.nwk', 'newick')
# Write multiple trees
Phylo.write(trees, 'all_trees.nwk', 'newick')
# Write to PhyloXML (preserves metadata)
Phylo.write(tree, 'output.xml', 'phyloxml')
# Write to Nexus
Phylo.write(tree, 'output.nex', 'nexus')
Serialize to String
tree = Phylo.read('tree.nwk', 'newick')
# Get tree as string (useful for embedding, logging, or API responses)
newick_string = format(tree, 'newick')
print(newick_string) # ((A:0.1,B:0.2):0.3,(C:0.4,D:0.5):0.6);
# Alternative method
newick_string = tree.format('newick')
# Other formats work too
phyloxml_string = format(tree, 'phyloxml')
Format Conversion
# Direct file conversion
Phylo.convert('input.nwk', 'newick', 'output.xml', 'phyloxml')
Phylo.convert('mrbayes.nex', 'nexus', 'trees.nwk', 'newick')
# Convert with processing
tree = Phylo.read('input.nwk', 'newick')
tree.ladderize() # Sort branches
Phylo.write(tree, 'sorted.nwk', 'newick')
Quick Tree Inspection
tree = Phylo.read('tree.nwk', 'newick')
# Print ASCII representation
print(tree)
# ASCII tree diagram
Phylo.draw_ascii(tree)
# Basic tree properties
print(f'Total branch length: {tree.total_branch_length()}')
print(f'Number of terminals: {len(tree.get_terminals())}')
print(f'Is bifurcating: {tree.is_bifurcating()}')
Accessing Tree Structure
# Get all terminal (leaf) nodes
terminals = tree.get_terminals()
for term in terminals:
print(f'{term.name}: branch_length={term.branch_length}')
# Get all internal nodes
nonterminals = tree.get_nonterminals()
# Get all clades (nodes)
all_clades = list(tree.find_clades())
# Find specific clade by name
clade = tree.find_any(name='Human')
Tree from Newick String Patterns
# Simple tree (no branch lengths)
tree = Phylo.read(StringIO('((A,B),(C,D));'), 'newick')
# With branch lengths
tree = Phylo.read(StringIO('((A:0.1,B:0.2):0.3,(C:0.4,D:0.5):0.6);'), 'newick')
# With internal node names
tree = Phylo.read(StringIO('((A,B)AB,(C,D)CD)root;'), 'newick')
# With bootstrap values (internal node names)
tree = Phylo.read(StringIO('((A:0.1,B:0.2)95:0.3,(C:0.4,D:0.5)80:0.6);'), 'newick')
Working with PhyloXML Metadata
# PhyloXML supports rich annotations
tree = Phylo.read('annotated.xml', 'phyloxml')
for clade in tree.find_clades():
if clade.confidences:
print(f'{clade.name}: confidence={clade.confidences[0].value}')
if hasattr(clade, 'taxonomy') and clade.taxonomy:
print(f'{clade.name}: taxonomy={clade.taxonomy.scientific_name}')
# Convert Newick to PhyloXML (adds metadata capabilities)
newick_tree = Phylo.read('simple.nwk', 'newick')
phyloxml_tree = newick_tree.as_phyloxml()
Handling Multiple Trees
# Parse bootstrap or posterior trees
trees = list(Phylo.parse('bootstrap.nwk', 'newick'))
print(f'Loaded {len(trees)} bootstrap trees')
# Process each tree
for i, tree in enumerate(trees):
print(f'Tree {i}: {len(tree.get_terminals())} taxa')
# Write subset of trees
Phylo.write(trees[:100], 'first_100.nwk', 'newick')
Iterating Over Large Tree Files
# Memory-efficient iteration (doesn't load all trees at once)
for tree in Phylo.parse('large_file.nwk', 'newick'):
if tree.total_branch_length() > 1.0:
print(f'Long tree: {tree.total_branch_length()}')
Common Newick Format Variations
| Input | Description |
|---|---|
(A,B,C); |
Unrooted, no lengths |
((A,B),C); |
Rooted topology |
(A:0.1,B:0.2); |
With branch lengths |
((A,B)X,C); |
Internal node named X |
((A,B):0.5[90],C); |
Branch with bootstrap |
Error Handling
from Bio import Phylo
from io import StringIO
# Check for valid newick
tree_string = '((A,B),(C,D));'
try:
tree = Phylo.read(StringIO(tree_string), 'newick')
print('Valid tree')
except Exception as e:
print(f'Parse error: {e}')
# Handle missing branch lengths
tree = Phylo.read('tree.nwk', 'newick')
for clade in tree.find_clades():
if clade.branch_length is None:
clade.branch_length = 0.0 # Set default
Format-Specific Notes
| Format | Strengths | Limitations |
|---|---|---|
| Newick | Universal, simple | No metadata |
| Nexus | PAUP/MrBayes compatible | Complex syntax |
| PhyloXML | Rich metadata, colors | Verbose |
| NeXML | Modern, extensible | Less common |
Related Skills
- tree-visualization - Draw and export tree figures
- tree-manipulation - Root, prune, and modify tree structure
- distance-calculations - Compute distances and build trees from alignments
- alignment/alignment-io - Read MSA files for tree construction
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