# -*- coding: utf-8 -*-
import random
from typing import Optional
from pybel import BELGraph
from pybel.struct.pipeline import transformation
from pybel.struct.utils import update_node_helper
from ..utils import safe_add_edge
__all__ = [
'random_by_nodes',
'random_by_edges',
'shuffle_node_data',
'shuffle_relations',
]
[docs]@transformation
def random_by_nodes(graph: BELGraph, percentage: Optional[float] = None) -> BELGraph:
"""Get a random graph by inducing over a percentage of the original nodes.
:param graph: A BEL graph
:param percentage: The percentage of edges to keep
"""
percentage = percentage or 0.9
assert 0 < percentage <= 1
nodes = graph.nodes()
n = int(len(nodes) * percentage)
subnodes = random.sample(nodes, n)
result = graph.subgraph(subnodes)
update_node_helper(graph, result)
return result
[docs]@transformation
def random_by_edges(graph: BELGraph, percentage: Optional[float] = None) -> BELGraph:
"""Get a random graph by keeping a certain percentage of original edges.
:param graph: A BEL graph
:param percentage: What percentage of eges to take
"""
percentage = percentage or 0.9
assert 0 < percentage <= 1
edges = graph.edges(keys=True)
n = int(graph.number_of_edges() * percentage)
subedges = random.sample(edges, n)
rv = graph.fresh_copy()
for u, v, k in subedges:
safe_add_edge(rv, u, v, k, graph[u][v][k])
update_node_helper(graph, rv)
return rv
[docs]@transformation
def shuffle_node_data(graph: BELGraph, key: str, percentage: Optional[float] = None) -> BELGraph:
"""Shuffle the node's data.
Useful for permutation testing.
:param graph: A BEL graph
:param key: The node data dictionary key
:param percentage: What percentage of possible swaps to make
"""
percentage = percentage or 0.3
assert 0 < percentage <= 1
n = graph.number_of_nodes()
swaps = int(percentage * n * (n - 1) / 2)
result: BELGraph = graph.copy()
for _ in range(swaps):
s, t = random.sample(result.node, 2)
result.nodes[s][key], result.nodes[t][key] = result.nodes[t][key], result.nodes[s][key]
return result
[docs]@transformation
def shuffle_relations(graph: BELGraph, percentage: Optional[str] = None) -> BELGraph:
"""Shuffle the relations.
Useful for permutation testing.
:param graph: A BEL graph
:param percentage: What percentage of possible swaps to make
"""
percentage = percentage or 0.3
assert 0 < percentage <= 1
n = graph.number_of_edges()
swaps = int(percentage * n * (n - 1) / 2)
result: BELGraph = graph.copy()
edges = result.edges(keys=True)
for _ in range(swaps):
(s1, t1, k1), (s2, t2, k2) = random.sample(edges, 2)
result[s1][t1][k1], result[s2][t2][k2] = result[s2][t2][k2], result[s1][t1][k1]
return result