I have a point with spatial and temporal coordinates
x=(lonx,latx,timex)
and I would like to find the nearest neighbour (according to some metric) amongst these other points
y1 = c(lony1,laty1,timey1)
y2 = c(lony2,laty2,timey2)
...
yn = c(lonyn,latyn,timeyn)
Is there any nearest-neighbour algorithm that I can use?