[R] find end of monotonic part of vector

[Rui Barradas]

Hello,

I should have continued, inline.

Às 15:05 de 07/08/20, Rui Barradas escreveu:
> Hello,
> 
> Maybe I'm not understanding but looking at this graph
> 
> 
> i <- diff(kalo.v$vodiv) > 0
> plot(kalo.v)
> lines(kalo.v)
> points(kalo.v$cas[i], kalo.v$vodiv[i], pch = 16, col = "red")
> 
> 
> it seems you want the point before the first local minimum?
> 
> 
> min(which(i)) - 1L
> #[1] 20
> 

(k <- min(which(i)) - 1L)
#[1] 20

kalo.v[k, ]
#                      cas  vodiv
#71230 2020-07-27 11:09:00 652.53


Rui Barradas

> 
> Hope this helps,
> 
> Rui Barradas
> 
> 
> Às 13:05 de 07/08/20, PIKAL Petr escreveu:
>> Hallo all
>>
>> I have such data
>>> dput(kalo.v)
>> structure(list(cas = structure(c(1595847000, 1595847060, 1595847120,
>> 1595847180, 1595847240, 1595847300, 1595847360, 1595847420, 1595847480,
>> 1595847540, 1595847600, 1595847660, 1595847720, 1595847780, 1595847840,
>> 1595847900, 1595847960, 1595848020, 1595848080, 1595848140, 1595848200,
>> 1595848260, 1595848320, 1595848380, 1595848440, 1595848500, 1595848560,
>> 1595848620, 1595848680, 1595848740, 1595848800, 1595848860, 1595848920,
>> 1595848980, 1595849040, 1595849100, 1595849160, 1595849220, 1595849280,
>> 1595849340, 1595849400, 1595849460, 1595849520, 1595849580, 1595849640
>> ), class = c("POSIXct", "POSIXt"), tzone = "UTC"), vodiv = c(999.9000244,
>> 999.9000244, 999.9000244, 999.9000244, 999.9000244, 999.9000244,
>> 999.9000244, 999.9000244, 999.9000244, 999.9000244, 999.9000244,
>> 999.9000244, 991.6404419, 925.2166748, 864.3446045, 812.1702271,
>> 758.9353027, 722.5073242, 684.5323486, 652.5300293, 82.18816376,
>> 141.1757813, 402.7521667, 999.9000244, 959.1779175, 967.0949707,
>> 517.1983643, 50, 50, 524.569458, 999.9000244, 999.9000244, 999.9000244,
>> 999.9000244, 999.9000244, 999.9000244, 999.9000244, 977.0491943,
>> 889.9714355, 999.9000244, 999.9000244, 999.9000244, 999.9000244,
>> 999.9000244, 999.9000244)), row.names = 71211:71255, class = 
>> "data.frame")
>>
>> and I would like to automatically find endpoint of gradually 
>> decreasing part
>> (here point 20, vodiv = 652.****).
>>
>> Usually I use diff but this is just a chunk of bigger data and diff 
>> seems to
>> be difficult to use. I appreciate any hint.
>>
>> Best regards.
>> Petr
>>
>>
>> ______________________________________________
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>> and provide commented, minimal, self-contained, reproducible code.
>>
> 
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide 
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.