I think the easiest way to do this is to set up a color vector with
ifelse and hand that off to the plot command: something like
col = ifelse(TEMP3[,"SITE"] == "BG1", "blue", "green") # Syntax is
ifelse(TEST, OUT_IF_TRUE, OUT_IF_FALSE)
For more complicated schemes, a set of nested ifelse()'s can get you
what you need. There are some other tricks with factors as well, but
they require a little more advanced use of R. Just for the record,
they'd look something like this:
X = letters[c(1,2,3,3,1,2,1,3,3,1,2,2,1)]
colX = c("red","green","blue")[as.factor(X)]
Hope this helps,
Michael
On Mon, Nov 21, 2011 at 2:17 PM, SarahH <sarah....@hotmail.co.uk> wrote:
> Dear All,
>
> I am very new to R - trying to teach myself it for some MSc coursework.
>
> I am plotting temperature data for two different sites over the same time
> period which I have downloaded from a university weather station data
> archive.
>
> I am using the following code to create the plot
>
> plot ( x = TEMP3[,"TIME"], y = TEMP3[,"TEMP"], type = "p", col =
> TEMP3[,"SITE"], pch = 3, main = "Temperature changes", xlab = "Date", ylab =
> "Temberature[C]")
>
> I managed to use col = TEMP3["SITE"] to plot the two different sites( BG1
> and EA7) in different colours, but I am struggling to change the colours.
>
> I wanted to up a colour scheme to match the site, so tried
>
> BG1 <- "blue"
> EA7 <- "green"
>
> before the plot function, but the graphic just came out with red and black
> as before.
>
> There are other datasets in which there are more than two sites so I would
> really like to learn how to use colour to distinguish between them on a
> plot.
>
> Any direction would be very greatly received!
>
> Thank you very much
>
> Sarah
>
>
>
>
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/Scatter-plot-using-colour-to-group-points-tp4092794p4092794.html
> Sent from the R help mailing list archive at Nabble.com.
>
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