Spatial-Temporal Graph Convolutional Gated Recurrent Network for Traffic Forecasting Le Zhao Mingcai Chen Yuntao Du Haiyang Yang Chongjun Wang

2025-05-03 0 0 1.18MB 9 页 10玖币
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Spatial-Temporal Graph Convolutional Gated Recurrent Network for Traffic
Forecasting
Le Zhao, Mingcai Chen, Yuntao Du, Haiyang Yang, Chongjun Wang
State Key Laboratory for Novel Software Technology at Nanjing University
Nanjing University, Nanjing 210023, China
2209557029@qq.com,
{chenmc, duyuntao, hyyang}@smail.nju.edu.cn,
chjwang@nju.edu.cn
Abstract
As an important part of intelligent transportation systems,
traffic forecasting has attracted tremendous attention from
academia and industry. Despite a lot of methods being pro-
posed for traffic forecasting, it is still difficult to model com-
plex spatial-temporal dependency. Temporal dependency in-
cludes short-term dependency and long-term dependency, and
the latter is often overlooked. Spatial dependency can be
divided into two parts: distance-based spatial dependency
and hidden spatial dependency. To model complex spatial-
temporal dependency, we propose a novel framework for traf-
fic forecasting, named Spatial-Temporal Graph Convolutional
Gated Recurrent Network (STGCGRN). We design an atten-
tion module to capture long-term dependency by mining peri-
odic information in traffic data. We propose a Double Graph
Convolution Gated Recurrent Unit (DGCGRU) to capture spa-
tial dependency, which integrates graph convolutional network
and GRU. The graph convolution part models distance-based
spatial dependency with the distance-based predefined adja-
cency matrix and hidden spatial dependency with the self-
adaptive adjacency matrix, respectively. Specially, we employ
the multi-head mechanism to capture multiple hidden depen-
dencies. In addition, the periodic pattern of each prediction
node may be different, which is often ignored, resulting in mu-
tual interference of periodic information among nodes when
modeling spatial dependency. For this, we explore the archi-
tecture of model and improve the performance. Experiments
on four datasets demonstrate the superior performance of our
model.
Introduction
Recently, many cities have been committed to developing
intelligent transportation systems (ITS) . As an important
part of ITS, traffic forecasting has attracted tremendous at-
tention from academia and industry. From the perspective of
traffic managers, traffic forecasting can help reduce conges-
tion and provide early warning for safety accidents. From the
traveler’s perspective, traffic forecasting can help plan travel
routes and improve travel efficiency.
Traffic forecasting is a time series forecasting problem,
using the past traffic data to predict the data in the future.
Early works simply deployed the classic time series analy-
sis models, e.g., history average (HA), vector auto regres-
sion (VAR), and auto regressive integrated moving average
Copyright © 2023
(ARIMA)(Ahmed and Cook 1979). These models can only
model the linear dependency in the data, while the traffic
data has complex nonlinear relationship, so the performance
of these linear models is poor in the real scenario. There-
fore, researchers shift to traditional machine learning meth-
ods, such as support vector regression (SVR)(Wu, Ho, and
Lee 2004) and k-nearest neighbors (KNN)(Davis and Ni-
han 1991). However, their performance relies heavily on the
handcrafted features, which need to be designed by domain
experts. Recently, deep learning models have become the
mainstream choice for traffic forecasting due to their auto-
matic feature extraction ability and better empirical perfor-
mance.
In deep learning, the temporal dependency of traffic data
can be modeled with recurrent neural networks (RNNs)(Fu,
Zhang, and Li 2016; Yu et al. 2017) or temporal convolution
modules(Zhang, Zheng, and Qi 2017; Yu, Yin, and Zhu 2018;
Wu et al. 2019). However, such approaches only mines short-
term dependency but ignores long-term dependency. Traffic
data has strong daily and weekly periodicity, which is crucial
for traffic forecasting. We can mine the periodicity in traffic
data to model long-term dependency in traffic data.
The spatial dependency can be captured by convolutional
neural network (CNN)(Fang et al. 2019; Lin et al. 2019; Yao
et al. 2019a) or graph convolutional networks (GCN)(Wu
et al. 2019; Wang et al. 2020; Bai et al. 2020). CNN can be
applied to grid-based maps to capture spatial dependency. In
this case, the data needs to be divided into
H×W
equal size
grids, where
H
and
W
represent the height and width of the
grid-based map respectively. However, CNN cannot handle
non-Euclidean data, which is a more common form when
describing road topology in real scenarios, with the predicted
positions as nodes and the roads as edges. GCN can process
non-Euclidean data, calculating the weight of the edge by
the distance between the nodes, obtaining a distance-based
predefined adjacency matrix, and then feeding it into GCN
to capture distance-based spatial dependency(Li et al. 2018;
Yu, Yin, and Zhu 2018). Besides, the self-adaptive adjacency
matrices can be used to model hidden spatial dependency(Wu
et al. 2019; Wang et al. 2020; Bai et al. 2020). However, there
may be multiple hidden spatial dependencies, which have not
been considered in existing works. In addition, the periodic
patterns of each prediction node may be different, which
need to be taken into account when modeling the spatial
arXiv:2210.02737v1 [cs.LG] 6 Oct 2022
dependency to prevent the periodic information of different
nodes from interfering with each other.
To solve the above problems, we propose Spatial-Temporal
Graph Convolutional Gated Recurrent Network (STGCGRN)
to improve the accuracy of traffic forecasting. Our contribu-
tions are as follows:
We propose a new framework to better exploit temporal
and spatial dependency: We capture long-term temporal
dependency by explicitly introducing daily and weekly
periodic data, which are fed into the attention module
with a sliding window. The DGCGRU layer is designed
to extract the distance-based spatial dependency and mul-
tiple hidden spatial dependencies, which are captured by
the predefined distance-based adjacency matrix and the
multi-head self-adaptive adjacency matrix, respectively.
We explore the model structure and find that mining the
periodic information of a single node, and then performing
spatial dependency modeling can reduce the interference
of periodic information among different nodes.
We conduct experiments on four datasets. The results
show that our model outperforms the baseline methods.
We also conduct ablation experiments to evaluate the im-
pact of each component of our model on the performance.
Related Work
Graph Convolutional Neural Network
Graph convolutional neural network is a special form of CNN
generalized to non-Euclidean data, which can be applied
to different tasks and domains, such as node classification
(Kipf and Welling 2017), graph classification (Ying et al.
2018), link prediction (Zhang and Chen 2018), node cluster-
ing (Wang et al. 2017), spatial-temporal graph forecasting,
etc. Bruna et al.(Bruna et al. 2014) is the first work to gen-
eralize the convolution operation to non-Euclidean data, and
proposes a spatial method and a spectral method.
Spatial-based approaches aggregate neighborhood feature
informations in the spatial domain to extract a node’s high-
level representation. DCNNs(Atwood and Towsley 2016) ex-
tend convolutional neural networks (CNNs) to general graph-
structured data by introducing a ‘diffusion-convolution’ op-
eration. Message Passing Neural Network (MPNN)(Gilmer
et al. 2017) describes a general framework for supervised
learning on graphs, applying graph convolution to super-
vised learning of molecules. GraphSage(Hamilton, Ying, and
Leskovec 2017) proposes a general inductive framework to
efficiently generate node embeddings for previously unseen
data, sampling and aggregating features from the node’s local
neighborhood.
Spectral-based approaches implement the convolution op-
eration in the spectral domain with graph Fourier transforms.
ChebyNet(Defferrard, Bresson, and Vandergheynst 2016)
achieves fast localized spectral filtering by introducing C
order Chebyshev polynomials parametrization. GCN(Kipf
and Welling 2017) further reduces computational complexity
of ChebNet by limiting C=2.
Traffic Forecasting
As an important component of ITS, traffic forecasting has
received wide attention for decades. Most of the early traf-
fic forecasting works are based on some classic time se-
ries analysis models. ARIMA (Ahmed and Cook 1979) is
used to predict the short-term freeway traffic data. Subse-
quently, many variants of ARIMA are applied to this task,
such as KARIMA (Van Der Voort, Dougherty, and Watson
1996), subset ARIMA (Lee and b. Fambro 1999), ARIMAX
(Williams 2001), etc. Traffic data contains complex spatial-
temporal dependency. However, the aforementioned works
only consider the linear relationship in the temporal dimen-
sion, which is obviously insufficient. Researchers apply tra-
ditional machine learning algorithms to traffic forecasting,
including SVR (Wu, Ho, and Lee 2004), KNN (Davis and
Nihan 1991), and so on. These methods need handcrafted
features, which require expert experience in related fields
Due to the advantages of deep learning in solving nonlin-
ear problems and automatically extracting features, scholars
pay more attention to deep learning. RNN (Fu, Zhang, and Li
2016; Yu et al. 2017) and CNN (Zhang, Zheng, and Qi 2017;
Yu, Yin, and Zhu 2018; Wu et al. 2019) are adopted to capture
temporal dependency. For example, Graph Wavenet (Wu et al.
2019) uses dilated casual convolutions to model the tempo-
ral dependency to increase the receptive field. To model the
spatial dependency, Some works (Fang et al. 2019; Lin et al.
2019; Yao et al. 2019a) divide the traffic data into grid-based
map, and extract spatial information by CNN. However, due
to natural limitations, CNN can not handle non-Euclidean
data. For this reason, researchers apply GCN to the field
of traffic forecasting. DCRNN (Li et al. 2018) captures the
spatial dependency using bidirectional random walks on the
graph. STGCN (Yu, Yin, and Zhu 2018) employs a gener-
alization of Chebnet to capture the spatial dependency of
traffic data. These methods only utilize the predefined graph
structures, which is not sufficient. Some works (Wu et al.
2019; Wang et al. 2020; Bai et al. 2020) calculate similari-
ties among learnable node embeddings to capture the hidden
spatial dependency in the data. DGCRN (Li et al. 2021a)
filters the node embeddings and then uses them to generate
dynamic graph at each time step. However, these works do
not adequately model spatial dependency and ignore periodic
information.
Preliminaries
Definition 1: Traffic Network. The traffic network is an
undirected graph
G= (V, E, A)
, where
V
is a set consists
of
N
nodes,
E
is a set of edges and
ARN×N
is the
adjacency matrix representing the nodes distance-based
proximity.
Definition 2: Traffic Signal Matrix. Traffic signal matrix
can be denoted as a tensor
XtRN×C
, where
C
is the
number of traffic features of each node (e.g., the speed,
volume), tdenotes the time step.
The problem of traffic forecasting can be described as:
given the traffic network
G= (V, E, A)
and
P
steps traf-
fic signal matrix
X(tP):t= (XtP, XtP+1, ..., Xt1)
RP×N×C
, learning a function
f
which maps
X(tP):t
摘要:

Spatial-TemporalGraphConvolutionalGatedRecurrentNetworkforTrafcForecastingLeZhao,MingcaiChen,YuntaoDu,HaiyangYang,ChongjunWangStateKeyLaboratoryforNovelSoftwareTechnologyatNanjingUniversityNanjingUniversity,Nanjing210023,China2209557029@qq.com,{chenmc,duyuntao,hyyang}@smail.nju.edu.cn,chjwang@nju.e...

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