Big Data

161Spatial Big Data

connected to s

2

in a spatial graph. Second, we dene a neighborhood based on a time

series as a temporal neighborhood. In Figure 8.7b, (s

2

; t

1

) and (s

2

; t

3

) are the temporal

neighbors of (s

2

; t

2

) if t

1

, t

2

, and t

3

are consecutive time slots. In addition, we dene

a neighborhood based on both space and time series as a spatial–temporal neighbor-

hood. In Figure 8.7b, (s

1

; t

1

), (s

1

; t

2

), (s

1

; t

3

), (s

2

; t

1

), (s

2

; t

3

), (s

3

; t

1

), (s

3

; t

2

), and (s

3

; t

3

) are

the spatial–temporal neighbors of (s

2

; t

2

) if s

1

and s

3

are connected to s

2

in a spatial

graph and t

1

, t

2

, and t

3

are consecutive time slots.

The test for detecting an outlier ...