R if in for loop error - how can I save selected model?

Question

I am new to R and have difficulties using "if" and "for-loop". sorry if it is duplicated.

as you can see a chuck of a code below, I try to create 100 lm models and save when the R is more than 0.7.

However, the code saved all 100 lm models.

I suspect the statement (!is.na(lm.cv.r[i]) < 0.60) is wrong but I cannot figure it out.

# lets use USArrests data as an example
data("USArrests")
head(USArrests)
df.norm <- USArrests


set.seed(100)
lm.cv.mse <- NULL
lm.cv.r <- NULL
k <- 100

for(i in 1:k){
    
    index.cv <- sample(1:nrow(df.norm),round(0.8*nrow(df.norm)))
    df.cv.train <- df.norm[index.cv, ]
    df.cv.test <- df.norm[-index.cv, ]
    
    lm.cv <- glm(Rape~., data = df.cv.train) 
    
    lm.cv.predicted <- predict(lm.cv, df.cv.test)
    
    lm.cv.mse[i] <- sum((df.cv.test$target - lm.cv.predicted)^2)/nrow(df.cv.test)
    lm.cv.r[i] <- as.numeric(round(cor(lm.cv.predicted, df.cv.test$target, method = "pearson"), digits = 3))
    
   
    if (!is.na(lm.cv.r[i]) > 0.70){
      saveRDS(lm.cv, file = paste("lm.cv", lm.cv.r[i], ".rds", sep = ''))
    }
}

Answer 1

I'm not familiarized with lm, so I will assume your code is working and the problem is as you said the if statement.

Try this out:

if ((lm.cv.r[i]>0.7) & (is.na(lm.cv.r[i])==FALSE)){
saveRDS(lm.cv, file = paste("lm.cv", lm.cv.r[i], ".rds", sep = ''))
}

So in your code

(!is.na(lm.cv.r[i]) > 0.70)

take a look at the !is.na(lm.cv.r[i]). Assuming that lm.cv.r[i] is a value or a set of values, then applying !is.na will return a value of TRUE since lm.cv.r[i] is not a na value. So you are dealing with this condition: " if TRUE > 0.7 ", which in fact returns TRUEsince 0.7 is less than 1.

In conclusion, you are saving every element since every if is TRUE.