r - Can we make prediction with nlxb from nlmrt package? -

i'm asking question because couldn't figure out why nlxb fitting function not work predict() function.

i have been looking around solve far no luck:(

i use dplyr group data , use do fit each group using nlxb nlmrt package.

here attempt

set.seed(12345) set =rep(rep(c("1","2","3","4"),each=21),times=1) time=rep(c(10,seq(100,900,100),seq(1000,10000,1000),20000),times=1) value <- replicate(1,c(replicate(4,sort(10^runif(21,-6,-3),decreasing=false)))) data_rep <- data.frame(time, value,set)  > head(data_rep)     #    time        value set     #1     10 1.007882e-06   1     #2    100 1.269423e-06   1     #3    200 2.864973e-06   1     #4    300 3.155843e-06   1     #5    400 3.442633e-06   1     #6    500 9.446831e-06   1     *      *       *         *    library(dplyr) library(nlmrt)      d_step <- 1     f <- 1e9     d <- 32           formula = value~ps*(1-exp(-2*f*time*exp(-d)))*1/(sqrt(2*pi*sigma))*exp(-(d-d_ave)^2/(2*sigma))*d_step        dffit = data_rep %>% group_by(set) %>%       do(fit = nlxb(formula ,                     data = .,                     start=c(d_ave=44,sigma=12,ps=0.5),                     control=nls.lm.control(maxiter = 100),                     trace=true)) 

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there 2 points finally,

1)first, how fitting coefficients of each group in continuation dffitpipeline.

2) doing prediction of based on new x values.

for instance range <- data.frame(x=seq(1e-5,20000,length.out=10000))

predict(fit,data.frame(x=range)

error in usemethod("predict") :    no applicable method 'predict' applied object of class "nlmrt" 

since nlxb working smoothly compared nls r-minpack-lmnls-lm-failed-with-good-results prefer solutions nlxb. if have better solution please let know.

there no coef or predict methods "nlmrt" class objects nlmrt package provide wrapnls run nlmrt , nls "nls" object results , object can used "nls" class methods.

also note nls.lm.control nlslm package , should not used here -- use list instead.