PLOC= list(LON=c(138.3152, 139.0214),
LAT=c(35.09047, 35.57324))
ax = seq(from=PLOC$LON[1], to=PLOC$LON[2], length=10)
ay = seq(from=PLOC$LAT[1], to=PLOC$LAT[2], length=10)
G = setplotmat(ax,ay)
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