Use this Skill for historical network analysis: correspondence networks, prosopographic data, temporal community detection, betweenness over time, and Gephi GEXF export.
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Use this Skill for historical network analysis: correspondence networks, prosopographic data, temporal community detection, betweenness over time, and Gephi GEXF export.
Historical Network Analysis: Prosopography and Correspondence Networks
TL;DR — Build correspondence networks from archival letter datasets, attach
prosopographic node attributes, compute temporal betweenness centrality by decade,
detect communities per period with Louvain, measure community persistence via Jaccard,
project bipartite person-event networks, and export to Gephi GEXF for visualization.
When to Use
Use this Skill when you need to:
Analyze the structure of historical correspondence networks (epistolary, diplomatic, merchant)
Study the rise and fall of influential intermediaries over decades or centuries
Detect scholarly, religious, or political communities across time periods
Visualize network evolution with node/edge attributes in Gephi
Project person × event membership matrices into person-person co-attendance networks
Do not use this Skill for:
Online social media graph analysis at millions-of-nodes scale (use GraphX or Snap.py)
Phylogenetic tree reconstruction (use dedicated bioinformatics tools)
Road or transport network optimization (use OR-Tools or igraph)
Background
Historical networks differ from modern social networks in two key ways:
Incompleteness: Only a fraction of historical correspondence survives. Network
metrics must be interpreted with an eye on archival gaps.
Temporal dynamics: Polities, alliances, and scholarly circles shift over decades.
Static network metrics hide this change; time-windowed analysis is essential.
Concept
Explanation
Prosopography
Systematic study of individuals in historical records; provides node attributes
Betweenness centrality
Fraction of shortest paths passing through a node; high = broker/gatekeeper
Louvain community detection
Modularity-maximizing algorithm; O(n log n)
Jaccard similarity
GEXF
Graph Exchange XML Format; native Gephi format supporting dynamic attributes
Bipartite projection
Person × event bipartite → person-person weighted unipartite graph
Step 1 — Letter Network from CSV with Temporal Betweenness
import networkx as nx
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
from collections import defaultdict
defbuild_correspondence_network(
letters_df: pd.DataFrame,
sender_col: str = "sender_id",
recipient_col: str = "recipient_id",
date_col: str = "year",
weight_threshold: int = 1,
) -> nx.MultiDiGraph:
"""
Construct a directed multigraph from a historical correspondence dataset.
Each letter becomes an edge with year and doc_id attributes.
Parallel edges are preserved (one edge per letter).
Args:
letters_df: DataFrame of letters with sender, recipient, year, doc_id columns.
sender_col: Column name for sender identifier.
recipient_col: Column name for recipient identifier.
date_col: Column name for the year integer.
weight_threshold: Minimum number of letters to include an edge in the graph.
Returns:
Directed multigraph with letter-level edges.
"""
G = nx.MultiDiGraph()
# Add all unique persons as nodes
all_persons = pd.concat([
letters_df[sender_col],
letters_df[recipient_col],
]).unique()
G.add_nodes_from(all_persons)
# Add edgesfor _, row in letters_df.iterrows():
G.add_edge(
row[sender_col],
row[recipient_col],
year=int(row[date_col]),
doc_id=str(row.get("doc_id", "")),
)
# Optionally collapse to weighted DiGraphif weight_threshold > 1:
simple = nx.DiGraph()
edge_weights = defaultdict(int)
for u, v, data in G.edges(data=True):
edge_weights[(u, v)] += 1for (u, v), w in edge_weights.items():
if w >= weight_threshold:
simple.add_edge(u, v, weight=w)
return simple
return G
defadd_prosopographic_attributes(
G: nx.Graph,
prosop_df: pd.DataFrame,
id_col: str = "person_id",
) -> nx.Graph:
"""
Add prosopographic metadata as node attributes to a network.
Args:
G: NetworkX graph with person IDs as nodes.
prosop_df: DataFrame with columns: person_id, name, title, birth_year,
death_year, gender, institution.
id_col: Column name for the person identifier.
Returns:
Graph with updated node attributes (modifies in place).
"""
attr_cols = [c for c in prosop_df.columns if c != id_col]
for _, row in prosop_df.iterrows():
pid = row[id_col]
if pid in G.nodes:
for col in attr_cols:
G.nodes[pid][col] = row[col]
return G
deftemporal_betweenness(
letters_df: pd.DataFrame,
decade_size: int = 10,
sender_col: str = "sender_id",
recipient_col: str = "recipient_id",
date_col: str = "year",
) -> pd.DataFrame:
"""
Compute betweenness centrality per decade window.
For each decade, build an undirected weighted graph from letters
in that window and compute normalized betweenness centrality.
Args:
letters_df: DataFrame of letters.
decade_size: Width of time window in years.
sender_col: Column for sender IDs.
recipient_col: Column for recipient IDs.
date_col: Column for year.
Returns:
DataFrame with columns: person_id, decade_start, betweenness.
"""
min_year = int(letters_df[date_col].min())
max_year = int(letters_df[date_col].max())
decades = range(min_year, max_year, decade_size)
records = []
for decade_start in decades:
decade_end = decade_start + decade_size
window = letters_df[
(letters_df[date_col] >= decade_start) &
(letters_df[date_col] < decade_end)
]
if window.empty:
continue# Build weighted undirected graph for this decade
G_dec = nx.Graph()
for _, row in window.iterrows():
u, v = row[sender_col], row[recipient_col]
if G_dec.has_edge(u, v):
G_dec[u][v]["weight"] += 1else:
G_dec.add_edge(u, v, weight=1)
if G_dec.number_of_nodes() < 3:
continue
bc = nx.betweenness_centrality(G_dec, weight="weight", normalized=True)
for person_id, score in bc.items():
records.append({
"person_id": person_id,
"decade_start": decade_start,
"betweenness": round(score, 6),
})
return pd.DataFrame(records)
defplot_betweenness_over_time(
betweenness_df: pd.DataFrame,
top_n: int = 5,
prosop_df: pd.DataFrame = None,
output_path: str = None,
) -> None:
"""
Line plot of top-N persons by peak betweenness centrality over decades.
Args:
betweenness_df: DataFrame from temporal_betweenness().
top_n: Number of top persons to highlight.
prosop_df: Optional prosopographic DataFrame; if given, use 'name' column.
output_path: If given, save figure here.
"""
peak_bc = (
betweenness_df.groupby("person_id")["betweenness"]
.max()
.sort_values(ascending=False)
.head(top_n)
)
top_persons = peak_bc.index.tolist()
fig, ax = plt.subplots(figsize=(11, 5))
for pid in top_persons:
sub = betweenness_df[betweenness_df["person_id"] == pid].sort_values("decade_start")
label = pid
if prosop_df isnotNoneand"name"in prosop_df.columns:
name_row = prosop_df[prosop_df.iloc[:, 0] == pid]
ifnot name_row.empty:
label = name_row.iloc[0]["name"]
ax.plot(sub["decade_start"], sub["betweenness"], marker="o", label=label)
ax.set_xlabel("Decade start")
ax.set_ylabel("Betweenness centrality (normalized)")
ax.set_title(f"Top {top_n} Brokers by Betweenness Centrality Over Time")
ax.legend(fontsize=8, loc="upper left")
ax.grid(True, alpha=0.3)
fig.tight_layout()
if output_path:
fig.savefig(output_path, dpi=150)
print(f"Betweenness plot saved to {output_path}")
plt.show()
Step 2 — Decade-by-Decade Community Detection and Persistence
import community as community_louvain
defdetect_communities_per_period(
letters_df: pd.DataFrame,
decade_size: int = 10,
sender_col: str = "sender_id",
recipient_col: str = "recipient_id",
date_col: str = "year",
resolution: float = 1.0,
) -> dict:
"""
Detect Louvain communities for each decade window.
Args:
letters_df: DataFrame of letters.
decade_size: Width of time window in years.
sender_col: Column for sender IDs.
recipient_col: Column for recipient IDs.
date_col: Column for year integer.
resolution: Louvain resolution parameter (>1 = more smaller communities).
Returns:
Dict mapping decade_start (int) → community_partition (dict: node → community_id).
"""
min_year = int(letters_df[date_col].min())
max_year = int(letters_df[date_col].max())
period_communities = {}
for decade_start inrange(min_year, max_year, decade_size):
decade_end = decade_start + decade_size
window = letters_df[
(letters_df[date_col] >= decade_start) &
(letters_df[date_col] < decade_end)
]
if window.empty:
continue
G_dec = nx.Graph()
for _, row in window.iterrows():
u, v = row[sender_col], row[recipient_col]
if G_dec.has_edge(u, v):
G_dec[u][v]["weight"] += 1else:
G_dec.add_edge(u, v, weight=1)
if G_dec.number_of_nodes() < 4:
continue
partition = community_louvain.best_partition(
G_dec, weight="weight", resolution=resolution, random_state=42
)
period_communities[decade_start] = partition
return period_communities
defcompute_community_jaccard_persistence(
period_communities: dict,
) -> pd.DataFrame:
"""
Measure the persistence of communities across consecutive periods using Jaccard similarity.
For each pair of consecutive periods, compute the maximum Jaccard similarity
between every community in period T and every community in period T+1.
High Jaccard = stable community; low Jaccard = community dissolved.
Args:
period_communities: Dict from detect_communities_per_period().
Returns:
DataFrame with columns: period_a, period_b, community_a, community_b,
jaccard, matched_count.
"""
periods = sorted(period_communities.keys())
records = []
for i inrange(len(periods) - 1):
pa = periods[i]
pb = periods[i + 1]
partition_a = period_communities[pa]
partition_b = period_communities[pb]
# Group nodes by communitydefgroup_by_comm(part):
groups = defaultdict(set)
for node, comm in part.items():
groups[comm].add(node)
return groups
groups_a = group_by_comm(partition_a)
groups_b = group_by_comm(partition_b)
for comm_a, nodes_a in groups_a.items():
best_jacc = 0.0
best_comm_b = Nonefor comm_b, nodes_b in groups_b.items():
intersection = len(nodes_a & nodes_b)
union = len(nodes_a | nodes_b)
jacc = intersection / union if union > 0else0.0if jacc > best_jacc:
best_jacc = jacc
best_comm_b = comm_b
records.append({
"period_a": pa,
"period_b": pb,
"community_a": comm_a,
"community_b": best_comm_b,
"jaccard": round(best_jacc, 4),
"size_a": len(nodes_a),
})
return pd.DataFrame(records)
Step 3 — GEXF Export for Gephi Visualization
defbuild_annotated_network_for_export(
letters_df: pd.DataFrame,
prosop_df: pd.DataFrame = None,
period_communities: dict = None,
sender_col: str = "sender_id",
recipient_col: str = "recipient_id",
date_col: str = "year",
) -> nx.Graph:
"""
Build a weighted undirected graph with full node/edge attributes for Gephi export.
Node attributes: name, gender, institution, community_id (from last period).
Edge attributes: weight (letter count), first_year, last_year.
Args:
letters_df: DataFrame of letters.
prosop_df: Optional prosopographic DataFrame.
period_communities: Optional dict from detect_communities_per_period().
sender_col: Column for sender IDs.
recipient_col: Column for recipient IDs.
date_col: Column for year.
Returns:
Annotated undirected NetworkX Graph ready for nx.write_gexf().
"""
G = nx.Graph()
# Build weighted edges
edge_data = defaultdict(lambda: {"weight": 0, "years": []})
for _, row in letters_df.iterrows():
u, v = str(row[sender_col]), str(row[recipient_col])
key = tuple(sorted([u, v]))
edge_data[key]["weight"] += 1
edge_data[key]["years"].append(int(row[date_col]))
all_nodes = set()
for (u, v), data in edge_data.items():
all_nodes.update([u, v])
G.add_edge(
u, v,
weight=data["weight"],
first_year=min(data["years"]),
last_year=max(data["years"]),
)
# Add prosopographic node attributesif prosop_df isnotNone:
id_col = prosop_df.columns[0]
for _, row in prosop_df.iterrows():
pid = str(row[id_col])
if pid in G.nodes:
for col in prosop_df.columns:
if col != id_col:
val = row[col]
if pd.notna(val):
G.nodes[pid][col] = str(val)
# Add community labels from the last periodif period_communities:
last_period = max(period_communities.keys())
partition = period_communities[last_period]
for node, comm_id in partition.items():
node_str = str(node)
if node_str in G.nodes:
G.nodes[node_str]["community"] = int(comm_id)
return G
defexport_gexf(
G: nx.Graph,
output_path: str,
) -> None:
"""
Export a NetworkX graph to GEXF format for Gephi visualization.
GEXF supports node/edge attributes and can encode dynamic networks
with time intervals. Open the output file directly in Gephi.
Args:
G: Annotated NetworkX graph.
output_path: Absolute path to write the .gexf file.
"""
nx.write_gexf(G, output_path)
print(f"GEXF file written to {output_path}")
print(f" Nodes: {G.number_of_nodes()}")
print(f" Edges: {G.number_of_edges()}")
print(f" Open in Gephi: File → Open → {output_path}")
Advanced Usage
Bipartite Person-Event Projection
defbuild_bipartite_person_event(
attendance_df: pd.DataFrame,
person_col: str = "person_id",
event_col: str = "event_id",
) -> tuple[nx.Graph, nx.Graph]:
"""
Build a bipartite person-event graph and project to person-person co-attendance.
Edge weight in the projected graph = number of events co-attended.
Args:
attendance_df: DataFrame with person_id and event_id columns.
person_col: Column for person identifiers.
event_col: Column for event identifiers.
Returns:
Tuple of (bipartite_graph, person_person_projection).
"""from networkx.algorithms import bipartite
B = nx.Graph()
persons = attendance_df[person_col].unique()
events = attendance_df[event_col].unique()
B.add_nodes_from(persons, bipartite=0)
B.add_nodes_from(events, bipartite=1)
for _, row in attendance_df.iterrows():
B.add_edge(row[person_col], row[event_col])
# Project onto persons (bipartite=0 set)
person_nodes = {n for n, d in B.nodes(data=True) if d.get("bipartite") == 0}
projected = bipartite.weighted_projected_graph(B, person_nodes)
return B, projected
Troubleshooting
Problem
Cause
Fix
ModuleNotFoundError: community
python-louvain not installed
pip install python-louvain
Betweenness very slow on large graph
O(n*m) algorithm
Use nx.betweenness_centrality(G, k=100) for approximate BC
GEXF file won't open in Gephi
Non-string node IDs
Cast all node IDs to str() before write_gexf()
Louvain non-deterministic results
Random seed not set
Pass random_state=42 to best_partition()
NetworkXError: Graph has no edges on thin decade
Very few letters in that window
Increase decade_size or skip windows with fewer than 5 edges
Community Jaccard all near 0
Network turnover too high
Check for person ID inconsistencies in source data
