Use value inside variable in dplyrs left_join

Question

I have a variable like this:

name = "ID"

and i want to use the value ("ID") to join a dataframe to another like this:

left_join(df1, df2, by=c(name = "col_to_join")

but I again don't know how to do this :/

with a little example

a = mtcars %>%
  select(1:3)

b = mtcars %>%
  select(3:5)

var_to_join = "disp"

# i know this could be done by just "disp"
# But the question is more on how to use a variable inside the by-argument
left_join(a, b, by = c(var_to_join = "disp"))

I don't understand - can you add a minimal reproducible example with the expected output? — Andrea M, Jun 21 '22 at 09:47
yes in this case it it, but lets imagine that the `var_to_join` would be something else — Lenn, Jun 21 '22 at 09:52

score 2 · Accepted Answer · answered Jun 21 '22 at 09:58

2

You can use stats::setNames() or rlang::set_names() to create a named vector:

var <- "bar"
setNames("foo", var)
#>   bar 
#> "foo"

answered Jun 21 '22 at 09:58

Lionel Henry

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Use value inside variable in dplyrs left_join

with a little example

1 Answers1