controlling x-axis time stamp on filled.contour plot - R

Question

I have been looking at the documentation but I cannot figure out how to control the time stamp on the x-axis of a filled.contour() plot in R. I have tried axis.POSIXct() and plot.axes = {}. But neither works for me.

Here is my simplified example:

x1 <- seq(as.Date("2016-01-01"),as.Date("2018-07-01"),by="month")
z1 <- c(0.45062130 ,0.51136174 ,0.6 ,0.8 ,0.29481738 ,0.6 ,0.27713756 ,0.62638512 ,0.23547530,0.29253901 ,0.75899501 ,0.67779756 ,0.51831742 ,0.08050147 ,0.71183739 ,0.13154414 ,0.79406706 ,0.13154414,0.03434758 ,0.59573892 ,0.22102821 ,0.13154414 ,0.13154414 ,0.13154414 ,0.13154414 ,0.13154414 ,0.23692593,0.95215104 ,0.38810846 ,0.17970580 ,0.05176054)
z2 <- z1^2
z3 <- z2^2
df <- data.frame(x1,z1,z2,z3)


time <- c(x1)
depths <- c(1,2,3)
temp2 <- as.matrix(data.frame(df$z1,df$z2,df$z3))
temp2<- matrix(temp2,ncol=ncol(temp2), dimnames = NULL)
filled.contour(time,depths,temp2, col=(matlab.like2(28)), 
               ylab="Depth", xlab="Time",
               key.title=title(expression('  Temp ('*degree*'C)')),xaxs="i")

Which outputs:

X-axis labels are in year format. I would like the format to be %b-%y for every month (e.g. May-16, June-16 etc). How do I do this?

Answer 1

Here's how to do it using the plot.axes option with axis.Date.

filled.contour(time,depths,temp2, #col=(matlab.like2(28)),
       ylab="Depth", xlab="Time",
       plot.axes = { axis.Date(side=1,x=time,at=time,format="%b-%y"); axis(2) },
       key.title=title(expression('  Temp ('*degree*'C)')),xaxs="i")