How to extract result from lme() function from multiple groups and then combine in R?

问题

First, the following data are split randomly into two groups according to the sl variable and then run the model for both groups using the for loop shown below the data set

mydata
              y  x sl
    1  5.297967  1  1
    2  3.322833  2  1
    3  4.969813  3  1
    4  4.276666  4  1
    5  5.972807  1  2
    6  6.619440  2  2
    7  8.045588  3  2
    8  7.377759  4  2
    9  6.907755  5  2
    10 8.672486  6  2
    11 8.283999  7  2
    12 8.455318  8  2
    13 7.414573  9  2
    14 8.634087 10  2
    15 7.356355  1  3
    16 6.606247  2  3
    17 6.396930  9  3
    18 6.579251 10  3
    19 5.521110  1  4
    20 2.224221  2  4
    21 6.742881  3  4
    22 6.709304  4  4
    23 6.875232  5  4
    24 8.476371  6  4
    25 7.360104  7  4

Runnign model using lme() function for both group and then store the beta coefficients as matrix and theta[ random intercept term ] as vector

sl.no=unique(mydata$sl)
m=length(unique(mydata$sl))
ngrp=2
set.seed(125)
idx=sample(1:ngrp, size=m, replace = T)

beta=matrix(NA, nrow = ngrp, ncol=3, byrow=T) #null matrix to store coefficients from both groups 
theta=rep(0,m) #null vector to store intercepts from both groups
library(nlme)
for ( g in 1:ngrp){
  rg=sl.no[idx==g]
  mydata_rG=mydata[mydata$sl %in% rg,] #Data set belongs to group-g


  lme_mod=lme(y~x+I(x^2),random = ~ 1|sl,
                  data = mydata_rG, method = "ML") #mixed effect model for each group


  beta[g,]=c(unlist(lme_mod$coefficients[1])[[1]],
             unlist(lme_mod$coefficients[1])[[2]],
             unlist(lme_mod$coefficients[1])[[3]])
  theta=c(unname(lme_mod$coefficients$random$sl))


}

I am expecting a theta vector of length m. Unfortunately, theta comes as the size of one. Any help is appreciated.

results of beta and theta

beta
         [,1]       [,2]        [,3]
[1,] 4.895805  0.7954474 -0.05602771
[2,] 6.423533 -1.7441753  0.32049662

theta
[1] 4.264366e-21 #it should be length of m.

回答1:

It's only about how you store theta values

sl.no=unique(mydata$sl)
m=length(unique(mydata$sl))
ngrp=2
set.seed(125)
idx=sample(1:ngrp, size=m, replace = T)

beta=matrix(NA, nrow = ngrp, ncol=3, byrow=T) 
theta=numeric() #Change here
library(nlme)
for ( g in 1:ngrp){
   rg=sl.no[idx==g]
   mydata_rG=mydata[mydata$sl %in% rg,] 

  lme_mod=lme(y~x+I(x^2),random = ~ 1|sl,
          data = mydata_rG, method = "ML") 


  beta[g,]=c(unlist(lme_mod$coefficients[1])[[1]],
             unlist(lme_mod$coefficients[1])[[2]],
             unlist(lme_mod$coefficients[1])[[3]])
   theta=c(theta, unname(lme_mod$coefficients$random$sl)) #Change here

}

来源：https://stackoverflow.com/questions/59709231/how-to-extract-result-from-lme-function-from-multiple-groups-and-then-combine

标签

extract

resultset