Creating a vector of beta values using a for loop

Question

I am a R-newcomer and currently trying to create 3 vectors consisting of the beta values of a multiple regression model. I have three predictors Age, Fitness and sleep and a dependent variable RT.

For each participant I have a excel table with 10 measurements at different time points. For each participant 1 to 20 I would like to save the betas of the multiple regression in the respective vector Age_betas, Fitness_betas or Sleep_betas.

In case I try my model for only one participant e.g.

model<-lm(scale(RT)~scale(Age)+scale(Fitness)+scale(Sleep), data=subset(Subjects1_5, Subject==1))

it works perfectly fine. Could someone help me why my loop won't work?

    Fun<-function()
  {  
  Age_betas<-c()
  Fitness_betas<-c()
  Sleep_betas<-c()

  for (counter in 1:5)

    {model<-lm(scale(RT)~scale(Age)+scale(Fitness)+scale(Sleep), data=subset(Subjects1_5, Dummy==1 & Subject==i))

    Age_betas <- c(Age_betas, model[["coefficients"]][["scale(Age)"]])

    Fitness_betas <- c(Fitness_betas, model[["coefficients"]][["scale(Fitness)"]])

    Sleep_betas <- c(Sleep_betas, model[["coefficients"]][["scale(Sleep)"]])} 
  }

There is no error, but the script doesn't do anything except adding the function fun.

Fun<-function() + {
+ Age_betas<-c() + Fitness_betas<-c() + Sleep_betas<-c() +
+ for (counter in 1:5) +
+ {model<-lm(scale(RT)~scale(Age)+scale(Fitness)+scale(Sleep), data=subset(Subjects1_5, Dummy==1 & Subject==i)) +
+ Age_betas <- c(Age_betas, model[["coefficients"]][["scale(Age)"]]) +
+ Fitness_betas <- c(Fitness_betas, model[["coefficients"]][["scale(Fitness)"]]) +
+ Sleep_betas <- c(Sleep_betas, model[["coefficients"]][["scale(Sleep)"]])} + }

Welcome to SO. Please provide a minimum reproducible example (https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example) with some test data. It would also be helpful if you were explaining what exactly does not work. Is there an error message? — Ben, Nov 28 '18 at 09:25
Unfortunately, I haven't yet found out how to upload data. So here the link to the file for 5 subjects [link](https://docs.google.com/spreadsheets/d/1dmcUntSn1x5e2VcWk6jCKwa7TdRGT3TsG1xNyh9-Hs4/edit?usp=sharing) — Max, Nov 28 '18 at 09:51
Are you aware of the difference between defining a function and calling a function? — Roland, Nov 28 '18 at 09:57
No. I really don't have an idea where things are going wrong and currently trying to read up on this — Max, Nov 28 '18 at 10:03
There are further issues, but your main problem is that you are defining a function but not calling it. You need to do `Fun()`. But first, you have to add a return value to your function definition. — Roland, Nov 28 '18 at 10:05

score 0 · Answer 1 · answered Nov 28 '18 at 10:41

Found out a way to solve the problem:

 age_betas<-c()
    fitness_betas<-c()
    sleep_betas<-c()

    for (i in 1:5){
      model<-lm(scale(RT)~scale(Age)+scale(Fitness)+scale(Sleep), data=subset(Subjects1_5, Dummy==1 & Subject==i))

      age_betas <- c(age_betas, model[["coefficients"]][["scale(Age)"]])
      fitness_betas <- c(fitness_betas, model[["coefficients"]][["scale(Fitness)"]])
      sleep_betas <- c(sleep_betas, model[["coefficients"]][["scale(Sleep)"]])
    }

score 0 · Answer 2 · answered May 13 '21 at 15:33

I believe what you desire your function to finally do is return the Age_betas, Fitness_betas and the Sleep_betas in their respective vectors. However, you haven't included in your user function the return() for an output. Also note that multi-argument returns are not permitted for the function; return().

What to do:

Create an empty list beta; this will be the list of lists where we store the beta vectors
Add the return function to output the beta list of lists
Then call the function Fun user-defined function to display the beta vectors.

Fun <- function(){
  beta <- list()
  
  for (counter in 1:5){
    model<-lm(scale(RT)~scale(Age)+scale(Fitness)+scale(Sleep), data=subset(Subjects1_5, Dummy==1 & Subject==i))
    beta[["Age_betas"]] = c(beta[["Age_betas"]], model[["coefficients"]][["scale(Age)"]])
    beta[["Fitness_betas"]] = c(beta[["Fitness_betas"]], model[["coefficients"]][["scale(Fitness)"]])
    beta[["Sleep_betas"]] = c(beta[["Sleep_betas"]], model[["coefficients"]][["scale(Sleep)"]])
  }
  return(beta)
}

# Call Function:
Fun()

The output:

# $Age_betas
# [1] -0.3970718 -0.3970718 -0.3970718 -0.3970718 -0.3970718

# $Fitness_betas
# [1] -0.004210636 -0.004210636 -0.004210636 -0.004210636 -0.004210636

# $Sleep_betas
# [1] -0.07401978 -0.07401978 -0.07401978 -0.07401978 -0.07401978

Creating a vector of beta values using a for loop

2 Answers2