How to Change X axis?
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I'm tryin to a graph in R covering the gold price movement for a 6 month period from December 2011 to June 2012 using  15 minute price observations, meaning I have 5913 observations
 I try modifying the x-axis to have dates labelled at the bottom as follows: 

    rt = dat$mid
    x11()
    plot(rt, type="l", col="blue", main="Gold Price", xlab="TBC", ylab="Yield", ylim=range(rt), xaxt="n")
    axis(1, at=1:7, lab=c("Dec '11", "Jan '12", "Feb '12", "Mar '12", "Apr '12", "May '12", "June '12"))

but this returns no axis at all. 

The default axis ranged: 0 1000 2000 3000 4000 5000 6000

I tried also changing `at` to `at=1:6000` but this is no help. Can anyone advise me of how to achieve this? Thanks