CCcheck {GEOmap} | R Documentation |
Check for counter-clockwise orientation for polygons. Positive is counterclockwise.
CCcheck(Z)
Z |
list(x,y) |
Uses sign of the area of the polygon to determine polarity.
j |
sign of area |
Based on the idea calculated area of a polygon.
Jonathan M. Lees<jonathan.lees@unc.edu>
Y=list() Y$x=c(170,175,184,191,194,190,177,166,162,164) Y$y=c(-54,-60,-60,-50,-26,8,34,37,10,-15) plot(c(160, 200),c(-85, 85), type='n') points(Y) lines(Y) CCcheck(Y) Z = list(x=rev(Y$x), y=rev(Y$y)) CCcheck(Z)