[R] problems with plot.data.frame

[Monica Pisica]

Hi list,

I have a question about 'plot'. I am trying to plot values registered every 
month - or every other month. If i build a data.frame called mydata like 
this (as an example)

jan   3   1   7
mar  2   4   2
may 1   3   2
jul    3   7   4
sep  5   2   3
nov  3   1   5

and use the command line:

plot(mydata[c(1,3)])

I get a graph that has on the x axis my months in alphabetical order - which 
i don't want, and instead of points i have thick horizontal lines. I've 
tried everything i could and understood from the R help files to give me 
points and on x axis the month in my order instead of alpha order. No 
success. What is the trick?

I fixed the month order by using numerals in front of them like 01, 03, ... 
etc, but this is not an elegant solution.

Any help will be much appreciated.

Monica