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

[Christopher W Ryan]

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
>>
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>>
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>
>

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