[R] Help

[APOLLOCHEROKEE]

Dear Sir or Madam:        Hi,sorry for disturbing you. Currently, I'm a master student, and my lecturer didn't teach us anything about how to use R. But the assignment is all about R. So even a very stupid error,I still can't tell. So please forgive my innocence.
The following is the requirement of my assignment
you will read in the data> > uscpi <- read.table("C:/Users/APOLLO/Desktop/ECC4660/A2/uscpi.csv",header=T,sep=",")> > # Now compute a variable called ss, short for subscript, which you> # can use to index your variables, which will be useful for differencing> > ss <- length(uscpi$year)> > # Compute what Julie Smith would refer to as the "1 year-ahead consumer> # price index" as simply the log of the price ratio between now and next> # year's observation> > inf <- log(uscpi$usdcpi2000[2:ss]/uscpi$usdcpi2000[1:(ss-1)])> > # You can take a look at the data with the following code> > plot(uscpi$year[2:ss],inf,type="b",ylim=c(0,0.15))error in xy.coords(x, y, xlabel, ylabel, log) :   'x' and 'y' lengths differ

Could you please tell me what's wrong with it? I have attached my data in this assignment.
Thank you very much 
Best regards 		 	   		  
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