Aligning contour line with contour filled plot irregular grid polar plot (semi circle)

Question

I see several people have answered the question for plotting with an irregular grid. I\'m having trouble getting the contour lines to line up with the filled contours. Als

Answer 1

The contours and colours do not align because filled.contour produces two plots (legend and contour). After plotting, these coordinate systems are lost. (?filled.contour). This can be solved by adding the relevant commands to the plot.axes argument. Semi-circles can be drawn with draw.arc from the plotrix package, spokes with segments. The zone within a minimum radius can be covered by white segments to represent no data.

# min distance of contours lines from center
min_dist=5

# position of spokes (degrees)
spk = seq(0,180,30)

filled.contour(x = fld$x,
               y = fld$y,
               z = fld$z,
               color.palette = colorRampPalette(c("white", "blue")),
               xlab = "",
               ylab = "",
               main = "Max",
               key.title = title(main = "Value", cex.main = 1),
               asp=1, xlim=c(0,40), ylim=c(-30,30),   frame.plot=F,
               plot.axes = {contour(fld$x, fld$y, fld$z , add=T, levels = seq(0,max(fld$z, na.rm=T),30), drawlabels=F, col=2);
                            # semi circles
                            draw.arc(x=0,y=0,radius = (1:3)*10, deg1=90, deg2=-90, col='grey');
                            # cover zone within minimum radius with (draw many closely spaced white lines
                            segments(x0 = 0, y0 = 0, x1 = sin((0:180)*pi/180)*min_dist, y1 = cos((0:180)*pi/180)*min_dist, col='white');
                            # spokes with labels
                            segments(x0 = 0, y0 = 0, x1 = sin(spk*pi/180)*30, y1 = cos(spk*pi/180)*30, col='grey');
                            text(x = sin(spk*pi/180)*30, y=cos(spk*pi/180)*30, labels = spk, pos=4, cex=0.6, xpd=NA)
                            # data points
                            points(x,y, pch=16, cex=0.6);
                            # x axis
                            axis(1);
                            # modified y axis
                            axis(2, at = axisTicks(range(y), log=F), labels = abs(axisTicks(range(y), log=F)), pos = 0);
               }
)