[R] Scatter plot - using colour to group points?

[R. Michael Weylandt]

I don't think you can do different colors for a single line (not an
ifelse thing, just a what would that mean sort of thing), but a plot
type like "b" "o" or "h" will work the same way.

Michael

On Mon, Nov 21, 2011 at 4:23 PM, SarahH <sarah.g10 at hotmail.co.uk> wrote:
> I got the colour vector with ifelse to work, great! Thank you.
>
> Is it possible to use the ifelse colour vector with other plot types? For
> example with type=l ? I tried but the graphic came back with blue lines for
> both sites and also a straight line connecting the start and end point of
> the data?
>
> Thanks
> Sarah
>
>
>
>
>
>
> Michael Weylandt wrote
>>
>> 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.g10 at .co> 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
>>>
>>>
>>>
>>>
>>>
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>>
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>
>
> --
> View this message in context: http://r.789695.n4.nabble.com/Scatter-plot-using-colour-to-group-points-tp4092794p4093337.html
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>
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