NOFE让数据降维能处理连续空间,比传统方法更保真、更稳定。
NOFE - Neural Operator Function Embedding

- 用图核算子学习函数间映射,支持任意位置插值,不依赖离散采样。
- 在气候数据上局部结构误差仅0.111,优于PCA的0.398和UMAP的0.791。
- 适合需要高精度、跨密度采样一致性的科学数据降维场景。
多数降维方法将数据视为离散点云,忽略了真实世界过程中的连续域结构。为此,我们提出神经算子函数嵌入(NOFE),一种面向连续域的降维框架。NOFE通过图核算子学习函数到函数的映射,可在任意查询位置进行无网格评估,且不依赖输入离散化。我们证明NOFE是层叠到层叠映射的近似,将层叠神经网络推广至连续域。在多个数据集上的实验表明,NOFE在局部结构保持方面显著优于主成分分析(PCA)、t-SNE和UMAP。以ERA5气候再分析数据为例,其局部应力仅为0.111,远低于PCA的0.398、t-SNE的0.773和UMAP的0.791。同时,NOFE展现出强采样独立性,在区域归一化下,拼接误差较UMAP降低20倍(59.0对267.6),并保证不同域块间的嵌入一致性。尽管全局结构保持略逊于PCA(Stress-1: 0.379 vs. 0.268),但能更好捕捉细微结构,生成平滑一致的嵌入,可泛化于不同采样密度,解决了离散降维方法的关键缺陷。
原文摘要 · Abstract (English)
Most dimensionality reduction methods treat data as discrete point clouds, ignoring the continuous domain structure inherent to many real-world processes. To bridge this gap, we introduce Neural Operator Function Embedding (NOFE), a domain-aware framework for continuous dimensionality reduction. NOFE learns function-to-function mappings via a Graph Kernel Operator, enabling mesh-free evaluation at arbitrary query locations independent of input discretization. We establish NOFE as approximation of sheaf-to-sheaf mappings, generalizing Sheaf Neural Networks to continuous domains. We evaluate NOFE across different datasets, comparing it against PCA, t-SNE, and UMAP. Our results demonstrate that NOFE significantly outperforms baselines in local structure preservation, achieving a local Stress of 0.111 compared to 0.398 for PCA, 0.773 for t-SNE, and 0.791 for UMAP for the ERA5 climate reanalysis dataset. NOFE also exhibits robust sampling independence, reducing the Patch Stitching Error by up to $20.0\times$ relative to UMAP (59.0 vs. 267.6 under regional normalization) and ensuring consistency across disjoint domain patches. While maintaining competitive global structure preservation (Stress-1: 0.379 vs. PCA's 0.268), NOFE resolves fine-grained structures and produces smooth, consistent embeddings that generalize across varying sample densities, addressing key limitations of discrete reduction methods.
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