[R] datetime on x-axis of plot

Hello, I'm reading Time Series Analysis and its Applilcations with R Examples and I have a question... I notice that in the book there are timeseries plots but without the x-axis being labeled with dates. They are just numbers 1,...50,...100, etc. How do I get the date to show up on the x-axis?

[R] rolling sum (like in Rmetrics package)

Hello, I'm new to R and would like to know how to create a vector of "rolling sums". (I have seen the Rmetrics package and the rollMean function and I would like to do the same thing except Sum instead of Mean.) I imagine someone has done this, I just can't find it anywhere. Example: x <- so