source("http://macosa.dima.unige.it/r.R")    # If I have not already loaded the library
---------- ---------- ---------- ---------- ---------- ---------- ---------- ----------

BF=4;HF=4;   PLANEww(-2.7,2.7, -2.7,2.7)
x <- c(-1,1,1,-1); y <- c(-1,-1,1,1)
polyD(x-1/4,y-1/4, -45, "blue"); polyD(x+1/4,y+1/4, 45, "brown")
text( 0.25, 1.5, "resident population", col="brown")
text(-0.25,-1.5, "present population", col="blue")
dart(1,0,2,0,"brown"); dart2(2,-0.4,"brown")
text(2.1,-0.75,  "temporary\nemigrants", col="brown")
dart(-1,0,-2,0,"blue"); dart2(-2,0.4,"blue")
text(-2.1,0.75, "temporary\nimmigrants", col="blue")

# With the text command I can put more sophisticated scripts than the ones that can be
# made with the type command. I can color them, put them in bold or italics, dimension
# them; with text(x,y,script, font=N) I have them in bold if N is 2, italics if 3, bold
# +italics if 4. text(…,cex=) with in  a number >1 / <1 (ie 0.8 and 1.2) yelds larger
# or smaller scripts. If I put \n a "new line" is inserted.
# If desired, I can align left or right of x,y with text(…,adj=0) or text(…,adj=1)
# I can tilt the scripts: text(…, srt=-90), text(…, srt=45) ("srt" is instead of "string
# rotation") rotate the script -90 or 45 with respect to the x axis direction.
BF=4;HF=4;   PLANEww(-2.7,2.7, -2.7,2.7)
# (first i should use PLANE to see the grid and then rewrite with PLANEww)
x <- c(-1,1,1,-1); y <- c(-1,-1,1,1)
polyS(x-1/4,y-1/4, -45, "blue"); polyS(x+1/4,y+1/4, 45, "brown")
text( 0.25, 1.5, "resident population", col="brown")
text(-0.25,-1.5, "present population", col="blue")
dart(1,0,2,0,"brown"); dart2(2,-0.4,"brown")
text(2.1,-0.75,  "temporary\nemigrants", col="brown")
dart(-1,0,-2,0,"blue"); dart2(-2,0.4,"blue")
text(-2.1,0.75, "temporary\nimmigrants", col="blue")
# dart2 and arrow2 join the tip of the last arrow with the new one
# The same goes for Dart2 and Arrow2; the blue arrows reproduced in black:
Dart(-1,0,-180,1,"black"); Dart2(90,0.4,"black")