R using distinct() with variable column header

Question

Suppose I have a dataframe:

> my.df <- data.frame(uid=c(1,1,3),somevalue=c("x","y","z"))
> my.df
   uid somevalue
1    1         x
2    1         y
3    3         z

I want:

  uid somevalue
1   1         y
2   3         z

I can't use

distinct(my.df, uid, .keep_all= TRUE)

because the variable name "uid" could change. However I have the variable name stored as a string.

So I get

> iKey <- "uid"
> distinct(my.df, iKey, .keep_all= TRUE)
  uid somevalue
1   1         x
2   1         y
3   3         z
Warning message:
Trying to compute distinct() for variables not found in the data:
- `iKey`
This is an error, but only a warning is raised for compatibility reasons.
The operation will return the input unchanged.

How can I get distinct() to use the value of iKey and not take it literally?

distinct will return 1st value of duplicate. See distinct(my.df, uid, .keep_all= TRUE) which is x for uid = 1. Do you want to return the last value of duplicate i.e y instead ? — Ronak Shah
– Ronak Shah, Commented Sep 24, 2020 at 2:12

Ronak Shah · Accepted Answer · 2020-09-24 02:10:44Z

1

We can use .data pronoun :

library(dplyr)
distinct(my.df, .data[[iKey]], .keep_all= TRUE)

#  uid somevalue
#1   1         x
#2   3         z

Or convert iKey to symbol with sym and evaluate it !!

distinct(my.df, !!sym(iKey), .keep_all= TRUE)

answered Sep 24, 2020 at 2:10

Ronak Shah

391k20 gold badges173 silver badges237 bronze badges

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

Comments

andrew_reece · Accepted Answer · 2020-09-24 03:27:52Z

1

The tidyselect across/all_of idiom works as well:

distinct(my.df, across(all_of(iKey)), .keep_all= TRUE)

answered Sep 24, 2020 at 3:27

andrew_reece

21.4k3 gold badges40 silver badges64 bronze badges

Collectives™ on Stack Overflow

R using distinct() with variable column header

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related