specify a variable name in a dataframe, using an element from list

Question

I'm trying to use an element from a list to specify a variable name in a dataframe. I know I can create a dataframe like this, creating variable A and C

list_A <- c(1,3,6,9,10)
List_C <- c(2,3,5,6,10)
df <- data.frame( A = list_A , C = List_C ) 
> df
   A  C
1  1  2
2  3  3
3  6  5
4  9  6
5 10 10

However, I'd like to specify the variable names from elements from a list, in this manner

nameslist <- c("A","B","C")
df <- data.frame( eval(parse(text=nameslist[1])) = List_A , eval(parse(text=nameslist[3])) = List_C )

I tried this, but cant get this code to run. Is there a way to adjust the "eval/parse" bit to make this work? Many thanks in advance.

Are you wedded to eval/parse? How about just: setNames(data.frame(sapply(nameslist, \(x) 1:5)), nameslist) — langtang
– langtang, Commented Apr 24, 2022 at 1:21

langtang · Accepted Answer · 2022-04-24 01:55:54Z

1

nameslist <- c("A","B","C")
setNames(data.frame(sapply(nameslist[c(1,3)], \(x) 1:5)), nameslist[c(1,3)])

Or, if you simply had a set of values_for_A and a set of values_for_C, you could do something like this:

setNames(data.frame(list(values_for_A, values_for_C)), nameslist[c(1,3)])

edited Apr 24, 2022 at 1:55

answered Apr 24, 2022 at 1:23

langtang

25.3k1 gold badge14 silver badges32 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Shaun Over a year ago

Thanks for this approach. However is this versatile?, what if the values in A and C are different (I only used 1:5 as an example). Can you give me an example code that would also work similarly for if it is, df <- data.frame( A = c(1,3,6,9,10) , C= c(2,3,5,6,10) ), I've just edited the above question accordingly

langtang Over a year ago

Sure, but the values have to come from somewhere. Are those values in a list too? I'm sorry, its not clear what you want. If you had the original values in a list, you could just directly convert to data.frame.

Shaun Over a year ago

can you use those values as they are specified above, c(1,3,6,9,10) and c(2,3,5,6,10). Or create a list for each call them List_A<- c(1,3,6,9,10) and List_C<-c(2,3,5,6,10), and reference them in.. I've edited question again to match

langtang Over a year ago

If you have them in those vectors, just make them into a list, wrap in data.frame, and wrap in setNames - see my edit

Collectives™ on Stack Overflow

specify a variable name in a dataframe, using an element from list

1 Answer 1

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related