# [R] How would I color points conditional on their value in a plot of a time series

Martin Maechler m@ech|er @end|ng |rom @t@t@m@th@ethz@ch
Wed May 2 10:01:11 CEST 2018

```>>>>> Eivind K Dovik <hello using eivinddovik.com>
>>>>>     on Tue, 1 May 2018 23:18:51 +0200 writes:

> You may also want to check this out:

> plot(ttt, type = "p")
> points(ttt, col = ifelse(ttt < 8, "black", "red"))

> Eivind K. Dovik
> Bergen, NO

yes, indeed,  or -- even nicer for a time series:
using  'type = "c"'  which many people don't know / have forgotten about:

ttt <- ts(rpois(12, lambda = 8), start = c(2000, 1), freq = 4)
plot  (ttt, type = "c")
points(ttt, col = ifelse(ttt < 8, "black", "red"))

Martin Maechler

> On Tue, 1 May 2018, Christopher W Ryan wrote:

>> Excellent! Worked like a charm. Thanks.
>>
>> --Chris Ryan
>>
>> On Tue, May 1, 2018 at 4:33 PM, William Dunlap <wdunlap using tibco.com> wrote:
>>
>>> The ts method for plot() is quirky.  You can use the default method:
>>>
>>> plot(as.vector(time(ttt)), as.vector(ttt), type = "p", col=ifelse(ttt<8,
>>> "black", "red"))
>>>
>>>
>>> Bill Dunlap
>>> TIBCO Software
>>> wdunlap tibco.com
>>>
>>> On Tue, May 1, 2018 at 1:17 PM, Christopher W Ryan <cryan using binghamton.edu>
>>> wrote:
>>>
>>>> How would I color points conditional on their value in a plot of a time
>>>> series.  Something like this:
>>>>
>>>> ## demonstration data
>>>> ttt <- ts(rpois(12, lambda = 8), start = c(2000, 1), freq = 4)
>>>> ttt
>>>> plot(ttt, type = "p")
>>>>
>>>> ## doesn't work--all points the same color
>>>> plot(ttt, type = "p", col = ifelse(ttt < 8, "black", "red"))
>>>>
>>>> ## also doesn't work--all points the same color
>>>> q <- as.numeric(ttt)
>>>> q
>>>> plot(ttt, type = "p", col = ifelse(q < 8, "black", "red"))
>>>>
>>>>
>>>> ## works OK with a simple, non-time-series scatterplot, as in
>>>>
>>>> sss <- data.frame(x = rpois(12, lambda = 8), y = rnorm(12, mean = 100, sd
>>>> =
>>>> 25))
>>>> with(sss, plot(y ~ x, col = ifelse(y > 100, "black", "red")))
>>>>
>>>> ## but I am missing something about time series.
>>>>
>>>> Thanks.
>>>>
>>>> --Chris Ryan
>>>> Broome County Health Department
>>>> and Binghamton University
>>>> Binghamton, NY
>>>>
>>>> [[alternative HTML version deleted]]
>>>>
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>>>
>>>
>>
>> [[alternative HTML version deleted]]
>>
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