# Traffico autostradale 2010-13 veicoli leggeri (auto, moto) in miliardi di km
traf <- c(4.5,4.3,4.9,5.5,5.5,5.7,6.8,7.1,5.7,5.2,4.5,4.7,
          4.5,4.2,4.7,5.4,5.3,5.7,6.8,6.9,5.7,5.2,4.3,4.8,
          4.2,3.4,4.6,4.9,4.9,5.4,6.3,6.5,5.4,4.7,4.2,4,4,
          4.0,3.5,4.3,4.6,4.8,5.3,6.2,6.6,5.3,4.6,4.2,4.4)
ang <- seq(30,30*12*4,30); A <- ang*pi/180
par( mai = c(0,0,0,0) )
plot(c(-8,8),c(-8,8),type="n",xlab="",ylab="",axes=FALSE,asp=1)
for (i in 1:7) symbols(0,0,circles=i, inches=FALSE, add=TRUE, fg="grey60")
rad <- function(x) x*pi/180; for(i in 1:6) abline(0,tan(rad(30*i)),lty=3)
# Congiungo i punti di coordinate polari A e traf con colori diversi per anno
lines(cos(A[1:12])*traf[1:12],sin(A[1:12])*traf[1:12],col="red")
lines(cos(A[12:24])*traf[12:24],sin(A[12:24])*traf[12:24],col="green4")
lines(cos(A[24:36])*traf[24:36],sin(A[24:36])*traf[24:36],col="blue")
lines(cos(A[36:48])*traf[36:48],sin(A[36:48])*traf[36:48],col="brown")
# Evidenzio con dei pallini i singoli dati
A1 <- A[1:12]; A2 <- A[13:24]; A3 <- A[25:36]; A4 <- A[37:48]
t1 <- traf[1:12]; t2 <- traf[13:24]; t3 <- traf[25:36]; t4 <- traf[37:48]
points(cos(A1)*t1,sin(A1)*t1,col="red",pch=19)
points(cos(A2)*t2,sin(A2)*t2,col="green4",pch=19)
points(cos(A3)*t3,sin(A3)*t3,col="blue",pch=19)
points(cos(A4)*t4,sin(A4)*t4,col="brown",pch=19)
# Metto i nomi di alcuni mesi, collocati opportunamente:
text(cos(A[1]+0.1)*7.5,sin(A[1]+0.1)*7.5,"Ge")
text(cos(A[4]+0.1)*7.5,sin(A[4]+0.1)*7.5,"Ap")
text(cos(A[7]+0.1)*7.5,sin(A[7]+0.1)*7.5,"Lu")
text(cos(A[10]+0.1)*7.5,sin(A[10]+0.1)*7.5,"Ot")
# Metto i nomi degli anni, collocati opportunamente:
text(6.5,6.5,"2010",col="red")
text(-6.5,6.5,"2011",col="green4")
text(-6.5,-6.5,"2012",col="blue")
text(6.5,-6.5,"2013",col="brown")
# Sono evidenti le caratteristiche dei diversi mesi