Knowledge Science Meets Politics. Unraveling Congressional Dynamics With… | by Luiz Venosa | Sep, 2024

Initially, we want information.

I downloaded information on all of the legal guidelines voted on and the way every member of Congress voted from 2023 to 2024 as much as Could 18th. All the info is offered on the Brazilian Congress’s open information portal. I then created two totally different pandas dataframes, one with all of the legal guidelines voted on and one other with how every congress member voted in every vote.

votacoes = pd.concat([pd.read_csv('votacoes-2023.csv', header=0, sep=';'),  pd.read_csv('votacoes-2024.csv', header=0, sep=';')])
votacoes_votos_dep = pd.concat([pd.read_csv('votacoesVotos-2023.csv', sep=';', quoting=1) , pd.read_csv('votacoesVotos-2024.csv', sep=';', on_bad_lines='warn', quoting=1, encoding='utf-8')])

To the votacoes dataframe, I chosen solely the entries with idOrgao of 180, which implies they had been voted in the primary chamber of Congress. So, we now have the info for the votes of most congress members. Then I used this the listing of the votacoes_Ids to filter the votacoes_votos_dep dataframe.

plen = votacoes[votacoes['idOrgao'] == 180]
votacoes_ids = plen['id'].distinctive()
votacoes_votos_dep = votacoes_votos_dep[votacoes_votos_dep['idVotacao'].isin(votacoes_ids)]

Now, within the votacoes_votos_dep, every vote is a row with the congress member’s identify and the voting session ID to establish who and what the vote refers to. Due to this fact, I created a pivot desk so that every row represents a congress member and every column refers to a vote, encoding Sure as 1 and No as 0 and dropping any vote the place greater than 280 deputies didn’t vote.

votacoes_votos_dep['voto_numerico'] = votacoes_votos_dep['voto'].map({'Sim': 1, 'Não':0})
votes_pivot = votacoes_votos_dep.pivot_table(index='deputado_nome', columns='idVotacao', values='voto_numerico').dropna(axis=1, thresh=280)

Earlier than computing the similarity matrix, I crammed all remaining NAs with 0.5 in order to not intrude with the positioning of the congress member. Lastly, we compute the similarity between the vectors of every deputy utilizing cosine similarity and retailer it in a dataframe.

from sklearn.metrics.pairwise import cosine_similarity
similarity_matrix = cosine_similarity(votes_pivot)
similarity_df = pd.DataFrame(similarity_matrix, index=votes_pivot.index, columns=votes_pivot.index)
Similarity Matrix – Picture By the Writer

Now, use the details about the voting similarities between congressmen to construct a community utilizing Networkx. A node will symbolize every member.

import networkx as nx

names = similarity_df.columns
# Create the graph as earlier than
G = nx.Graph()
for i, identify in enumerate(names):
G.add_node(identify)

Then, the sides connecting two nodes symbolize a similarity of at the very least 75% of the 2 congressmen’s voting habits. Additionally, to deal with the truth that some congress members have dozens of friends with excessive levels of similarity, I solely chosen the primary 25 congressmen with the very best similarity to be given an edge.

threshold = 0.75
for i in vary(len(similarity_matrix)):
for j in vary(i + 1, len(similarity_matrix)):
if similarity_matrix[i][j] > threshold:
# G.add_edge(names[i], names[j], weight=similarity_matrix[i][j])
counter[names[i]].append((names[j], similarity_matrix[i][j]))
for supply, goal in counter.objects():
selected_targets = sorted(goal, key=lambda x: x[1], reverse=True)[:26]
for goal, weight in selected_targets:
G.add_edge(supply, goal, weight=weight)

To visualise the community, you have to resolve the place of every node within the airplane. I made a decision to make use of the spring structure, which makes use of the sides as springs holding nodes shut whereas making an attempt to separate. Including a seed permits for reproducibility since it’s a random course of.

pos = nx.spring_layout(G, ok=0.1,  iterations=50, seed=29)

Lastly, we plot the community utilizing a Go determine and individually add the sides and nodes based mostly on their place.


# Create Edges
edge_x = []
edge_y = []
for edge in G.edges():
x0, y0 = pos[edge[0]]
x1, y1 = pos[edge[1]]
edge_x.prolong([x0, x1, None])
edge_y.prolong([y0, y1, None])

# Add edges as a scatter plot
edge_trace = go.Scatter(x=edge_x, y=edge_y, line=dict(width=0.5, colour='#888'), hoverinfo='none', mode='strains')
# Create Nodes
node_x = []
node_y = []
for node in G.nodes():
x, y = pos[node]
node_x.append(x)
node_y.append(y)

# Add nodes as a scatter plot
node_trace = go.Scatter(x=node_x, y=node_y, mode='markers+textual content', hoverinfo='textual content', marker=dict(showscale=True, colorscale='YlGnBu', measurement=10, colour=[], line_width=2))

# Add textual content to the nodes
node_trace.textual content = listing(G.nodes())

# Create a determine
fig = go.Determine(information=[edge_trace, node_trace],
structure=go.Structure(showlegend=False, hovermode='closest', margin=dict(b=0,l=0,r=0,t=0), xaxis=dict(showgrid=False, zeroline=False, showticklabels=False), yaxis=dict(showgrid=False, zeroline=False, showticklabels=False)))

fig.present()

Outcome:

Picture by the Writer

Properly, it’s an excellent begin. Completely different clusters of congressmen might be seen, which means that it precisely captures the political alignment and alliances in Congress. However it’s a mess, and it’s unimaginable to actually discern what’s happening.

To enhance the visualization, I made the identify seem solely while you hover over the node. Additionally, I coloured the nodes in response to the political events and coalitions accessible on Congress’s web site and sized them based mostly on what number of edges they’re related to.

Picture by the Writer

It’s loads higher. We now have three clusters, with some nodes between them and some larger ones in every. Additionally, in every cluster, there’s a majority of a selected colour. Properly, let’s dissect it.