Loop over all 'test' with R

Question

I made a new dataset which only have the variables:

I have then added a new variable to my data set, called Item:

d <- test[, . (ID, age, test= test)]

My question is now, that I want to make a function that will make a loop over all questions i have ? is that possible?

do you have a sample of the `lmh14` so we can see what the data looked like before? — RyanF, Aug 31 '22 at 12:45
What do you want to do in this loop? Most functions in R are vectorized so you usually don't need to write a look yourself. It's not clear to me what you are trying to do. It's easier to help you if you provide a [reproducible example](https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example) with sample input and desired output that can be used to test and verify possible solutions. — MrFlick, Aug 31 '22 at 12:53
And how would you like question number displayed in the output table? — RyanF, Aug 31 '22 at 12:53

score 2 · Answer 1 · answered Aug 31 '22 at 12:59

Here is a sample set with only 2 questions. You can modify this to extend to 85.

In this case, I am using the melt( ) function in the data.table package to convert the data from wide format to long format. The id.vars are variables you would like to keep as columns and the measure.vars are variables you would like condensed into a new column Question with corresponding values in Response.

library(data.table)

lmh14 <- data.table(
  ID = c(1,2,3,4),
  education_code = c(20,50,20,60),
  age = c(87,67,56,52),
  sex = c("F","M","M","M"),
  question1 = c(NA_real_,1,5,3),
  question2 = c(4,3,5,NA_real_))

lmh14_v2 <- melt(
  data = lmh14,
  id.vars = c("ID","education_code","sex"),
  measure.vars = c("question1","question2"),
  variable.name = "Question",
  value.name = "Response")

lmh14_v2
   ID education_code sex  Question Response
1:  1             20   F question1       NA
2:  2             50   M question1        1
3:  3             20   M question1        5
4:  4             60   M question1        3
5:  1             20   F question2        4
6:  2             50   M question2        3
7:  3             20   M question2        5
8:  4             60   M question2       NA

But that is not what I want - I want the same data set as showed - item is only based on question1 but I need to make a for loop or a function over all 'item' (all questions) ? :) — Hellihansen, Aug 31 '22 at 13:05
yes but i dont want to manually do the lines 87 times - but a function that does it for me :) — Hellihansen, Aug 31 '22 at 13:34

score 0 · Answer 2 · answered Aug 31 '22 at 13:46

0

Although the assign function is not the best, here is a loop that can do this for you.

for (Question in 1:2) {
  assign(
    x = paste0("Question",Question),
    value = lmh14[,.(ID, education_code, age, sex, item = get(paste0("question",Question)))])
}

answered Aug 31 '22 at 13:46

RyanF

119
6

Thank you! not to be difficult - what can I do if i have some values called "Question1", "question1_1" and "question1_text" - can this be included in the loop? – Hellihansen Sep 01 '22 at 06:59

Loop over all 'test' with R

2 Answers2