【DGL系列】dgl中为graph指定CSR/COO/CSC矩阵格式

g = dgl.graph(([0, 0, 1], [2, 3, 2]))
g.ndata['h'] = torch.ones(4, 1)

# 查看格式
g.formats()
# => {'created': ['coo'], 'not created': ['csr', 'csc']}

# 指定一种格式
csr_g = g.formats('csr')
csr_g.formats()
# => {'created': ['csr'], 'not created': []}

# 指定多种格式
new_g = g.formats(['coo', 'csr'])
new_g .formats()
# => {'created': ['coo', 'csr'], 'not created': []}

g = dgl.graph(([0, 0, 1], [2, 3, 2]))
g.ndata['h'] = torch.ones(4, 1)

# 假设只有一种格式
g.formats()
# => {'created': ['coo'], 'not created': ['csc']}

# 交集没有csr，就不会设置成功
new_g = g.formats(['coo', 'csr'])
new_g .formats()
# => {'created': ['coo'], 'not created': []}

g = dgl.graph(([0, 0, 1], [2, 3, 2]))
g.ndata['h'] = torch.ones(4, 1)

# 假设只有一种coo格式
g.formats()
# => {'created': ['coo'], 'not created': ['csc']}

# 交集没有csr，就不会设置成功
new_g = g.formats(['coo', 'csr'])
new_g .formats()
# => {'created': ['coo'], 'not created': ['csr']}

# 显式创建格式
new_g.create_formats_()
print(new_g.formats())
# => {'created': ['coo', 'csr'], 'not created': []}

import dgl
import pickle

# 创建一个图并设置多种格式
g = dgl.graph(([0, 1, 2], [1, 2, 3]))
g = g.formats(['coo', 'csr', 'csc'])

# 使用 pickle 保存
with open('graph.pkl', 'wb') as f:
    pickle.dump(g, f)

# 使用 pickle 加载
with open('graph.pkl', 'rb') as f:
    loaded_g = pickle.load(f)

# 检查加载后的格式
print(loaded_g.formats())  # 可能会丢失某些格式

# 保存图
dgl.save_graphs("graph.bin", [graph])

# 加载图
loaded_graphs, _ = dgl.load_graphs("graph.bin")
graph = loaded_graphs[0]