CODEWITHSUNDEEP
rdplyr
DeduciveR
DeduciveR

Reputation: 1702

How to subset columns with dplyr select dependent upon values in columns in a one row dataframe

I have a single row dataframe:

df <- structure(list(who = "Tom", who2 = "Tom", who3 = "Harry", how_many = 48, 
                 reserve = "Mary"), class = c("tbl_df", "tbl", "data.frame"
                 ), row.names = c(NA, -1L))

# A tibble: 1 x 5
  who   who2  who3  how_many reserve
  <chr> <chr> <chr>    <dbl> <chr>  
1 Tom   Tom   Harry       48 Mary

I'd like to subset columns by condition, but I get the error: Error: condition must be a logical, not list from the code below.

df %>% 
 if_else(who == who2, select(who3), select(how_many, reserve))

I think I understand why I'm getting the error - this code would not be valid if there was more than 1 row, but can't think of another way how to do this in a chain of dplyr piped functions.

Upvotes: 0

Views: 139

Answers (1)

MrFlick
MrFlick

Reputation: 206197

One way it to pipe the data into an expression block and then run more standard code to conditionally select what columns you want.

df %>% {if (pull(., who )==pull(., who2 )) {
  select(., who3)
} else {
  select(., how_many, reserve)
}}

Upvotes: 3

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