Re: [R] Obtain gradient at multiple values for exponential decay model

2018-04-06 Thread Jeff Newmiller
I have never found the R symbolic differentiation helpful because my functions are typically quite complicated, but was prompted by Steve Ellison's suggestion to try it out in this case: # reprex (see reprex package) graphdta <- read.csv( text = "t,c 0,100 40,78 80,59 120,38 160

Re: [R] Fast tau-estimator line does not appear on the plot

2018-04-06 Thread Jeff Newmiller
You need to pay attention to the documentation more closely. If you don't know what something means, that is usually a signal that you need to study more... in this case about the difference between an input variable and a design (model) matrix. This is a concept from the standard linear algebra

Re: [R] Fast tau-estimator line does not appear on the plot

2018-04-06 Thread varin sacha via R-help
R-experts, I have fitted many different lines. The fast-tau estimator (yellow line) seems strange to me because this yellow line is not at all in agreement with the other lines (reverse slope, I mean the yellow line has a positive slope and the other ones have negative slope). Is there somethi

Re: [R] Obtain gradient at multiple values for exponential decay model

2018-04-06 Thread David Winsemius
> On Apr 6, 2018, at 8:15 AM, David Winsemius wrote: > >> >> On Apr 6, 2018, at 8:03 AM, David Winsemius wrote: >> >> >>> On Apr 6, 2018, at 3:43 AM, g l wrote: >>> Sent: Friday, April 06, 2018 at 5:55 AM From: "David Winsemius" Not correct. You already have `pr

Re: [R] Obtain gradient at multiple values for exponential decay model

2018-04-06 Thread David Winsemius
> On Apr 6, 2018, at 8:03 AM, David Winsemius wrote: > > >> On Apr 6, 2018, at 3:43 AM, g l wrote: >> >>> Sent: Friday, April 06, 2018 at 5:55 AM >>> From: "David Winsemius" >>> >>> >>> Not correct. You already have `predict`. It is capale of using the >>> `newdata` values to do interpola

[R] Revolutions blog roundup: March 2018

2018-04-06 Thread David Smith (CDA) via R-help
Since 2008, Microsoft staff and guests have written about R at the Revolutions blog (http://blog.revolutionanalytics.com) and every month I post a summary of articles from the previous month of particular interest to readers of r-help. In case you missed them, here are some articles related to R f

Re: [R] Obtain gradient at multiple values for exponential decay model

2018-04-06 Thread David Winsemius
> On Apr 6, 2018, at 3:43 AM, g l wrote: > >> Sent: Friday, April 06, 2018 at 5:55 AM >> From: "David Winsemius" >> >> >> Not correct. You already have `predict`. It is capale of using the `newdata` >> values to do interpolation with the values of the coefficients in the model. >> See: >>

Re: [R] Obtain gradient at multiple values for exponential decay model

2018-04-06 Thread S Ellison
> coef(graphmodeld) >(Intercept) graphdata[, 1] >4.513544204 -0.006820623 > > This corresponds to the linear model but it is still not understood how this > helps > to determine gradients at specific points for the exponential model. You have fitted log(y) against x. Your fitted linear

Re: [R] Obtain gradient at multiple values for exponential decay model

2018-04-06 Thread g l
> Sent: Friday, April 06, 2018 at 1:44 PM > From: "Jeff Newmiller" > > You did not try my suggestion. You tried David's, which has a leftover > mistake from your guesses about what the argument to coef should be. Yes, sorry for the mistake. coef(graphmodeld) (Intercept) graphdata[, 1] 4.

Re: [R] Obtain gradient at multiple values for exponential decay model

2018-04-06 Thread Jeff Newmiller
You did not try my suggestion. You tried David's, which has a leftover mistake from your guesses about what the argument to coef should be. -- Sent from my phone. Please excuse my brevity. On April 6, 2018 3:30:10 AM PDT, g l wrote: >> Sent: Friday, April 06, 2018 at 4:53 AM >> From: "Jeff Newm

Re: [R] Obtain gradient at multiple values for exponential decay model

2018-04-06 Thread g l
> Sent: Friday, April 06, 2018 at 5:55 AM > From: "David Winsemius" > > > Not correct. You already have `predict`. It is capale of using the `newdata` > values to do interpolation with the values of the coefficients in the model. > See: > > ?predict > The § details did not mention interpola

Re: [R] Obtain gradient at multiple values for exponential decay model

2018-04-06 Thread g l
> Sent: Friday, April 06, 2018 at 4:53 AM > From: "Jeff Newmiller" > To: "g l" > coef( graphmodeld ) > coef(graphmodelp) Error: $ operator is invalid for atomic vectors A quick search engine query revealed primarily references to the dollar sign ($) operator which does not seem relevant to th