[R] Unexpected Gap in simple line plot
Duncan Murdoch
murdoch.duncan at gmail.com
Fri Jan 21 02:26:28 CET 2011
On 20/01/2011 8:12 PM, D Kelly O'Day wrote:
>
> I am getting an unexpected gap in a simple plot of monthly data series.
>
> I have created a csv file of monthly climate observations that I store
> on-line. When I download the csv file and plot one of the series, I get a
> gap even though there is data for the missing point.
>
> Here is a snippet to show the problem.
>
> ## Strange plot results
> link<- "http://processtrends.com/files/RClimate_CTS_latest.csv"
> cts<- read.csv(link, header=T)
>
> ## Simple line plot - gap for no reason
> plot(cts$yr_frac, cts$GISS, type="l", xlim=c(1982, 1983),xaxs="i",
> yaxs="i")
>
> ## May, 1982 observation missing
> ## Add points to plot in red, to see if May shows up
> points(cts$yr_frac, cts$GISS, type="p", col="red")
> ## yes, May shows up in points
>
> ## Look at cts data.frame. No obvious problems to me??
> small<- subset(cts, cts$yr_frac>1982& cts$yr_frac<1983)
> small[,c(1,3)]
>
> The same problem occurs in the other data vectors (HAD, NOAA, RSS, UAH, etc)
>
> I have not been able to figure why I am getting the gap and how to show a
> continuous line through May, 1982 data points.
>
> Any suggestions?
Look at the data, not a subset of the data. Printing cts, I see the
following:
1226 1982.12 198202 0.07 -0.033 0.0801 -0.099 -0.201 0.1219 0.674 -0.052
1227 1982.21 198203 -0.12 -0.123 0.0265 -0.167 -0.347 0.1262 0.503 -0.052
1228 4.00 NA NA NA NA NA NA NA NA NA
1229 1982.29 198204 -0.03 0.024 0.1508 -0.116 -0.236 0.1311 0.495 -0.150
1230 5.00 NA NA NA NA NA NA NA NA NA
1231 1982.38 198205 0.10 0.041 0.1268 -0.228 -0.236 0.1730 0.876 -0.168
You get a better view in the data editor, seen by edit(cts) (on Windows,
but I think it works on other systems too...)
There are a couple of weird records with NA values around the gap. NA
in a line plot causes a gap in the line.
Duncan Murdoch
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