residuals[abs(residuals) > (2*sd)]

gcm <

[hidden email]> wrote on 07/16/2012 07:07:31 AM:

> Jean, how would you modify your function to grab all the selected

> and not just the first?

> Thank you so much!

>

> From: Jean V Adams [via R] [

mailto:

[hidden email]]

> Sent: Thursday, July 12, 2012 4:59 PM

> To: Lauren Vogric

> Subject: Re: Grabbing Indexes of a certain standard deviation

>

> I wrote a little function called first() to help with situations like

> this. It returns a 1 every time an element of a vector is different

from

> the previous element, and a 0 otherwise.

>

> first <- function(x) {

> L <- length(x)

> c(1, 1-(x[-1]==x[-L]))

> }

>

> sd <- 1

> residuals <- c(1, 2.1, 3, 4, 3, 1, 0, -4, -1)

> # logical, indicating if the residual exceeds 2 standard deviations

> exceed <- abs(residuals) > (2*sd)

> # indices of the first exceeding residual of a series

> which(first(exceed) & exceed)

>

> Jean

>

>

> gcm <[hidden email]</user/SendEmail.jtp?type=node&node=4636370&i=0>>

> wrote on 07/12/2012 11:07:49 AM:

>

> > I have a graph of residuals and I am attempting to get a list of the

> indexes

> > of each time the residual is greater than 2 standard deviations or

less

> than

> > -2 standard deviations, but only the first point of the section. And

> then

> > I'd also need the first point where the point returns to the range

> between

> > +/- 2 standard deviations.

> > So basically if my standard deviation=1 and my residuals=c(1, 2.1, 3,

4,

> 3,

> > 1, 0, -4, -1) I want it to grab the second number, where it exceeds 2

> > standard deviations and the 6th where it returns to less than 2

standard

> > deviations. Also, it would grab -4 (or residuals[ 8]) and -1

> (residuals[9])

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