Error in dplyr summarise by groups

[tinaR]

Hi,

when trying to summarise median values by a categorical variable (here, cognitive_status) using the dplyr package, in some cases I get a error warning (for most of the variables it works fine!)

I'd appreciate some help,

Thanks!

dat %>%
group_by(cognitive_status) %>%
summarize(medn = median(dt_alph_gs, na.rm = T))

Error: Problem with summarise() input medn.
x Input medn must return compatible vectors across groups
Result type for group 1 (cognitive_status = "No cognitive impairment"): .
Result type for group 2 (cognitive_status = "MCI"): .
Input medn is median(dt_alph_gs, na.rm = T).

[nirgrahamuk]

To help us try to understand your error could you try to share a small sample of the data in question?
some code like this should work:

dat %>% 
select(cognitive_status, dt_alph_ga) %>% 
sample_n(size=10,  replace = FALSE) %>% 
dput()

[tinaR]

@nirgrahamuk

dat %>% 
select(cognitive_status, dt_alph_ga) %>% 
sample_n(size=10,  replace = FALSE) %>% 
dput()

Hi,

thanks so much for your reply.

this is the output that I get:

dat %>%

• select(cognitive_status, dt_alph_gs) %>% 
  

• sample_n(size=10,  replace = FALSE) %>% 
  

• dput()
  

structure(list(cognitive_status = structure(c(2L, 2L, 1L, 2L,
1L, 1L, 2L, 1L, 2L, 2L), .Label = c("No cognitive impairment",
"MCI"), label = "Cognitive status group", class = c("labelled",
"factor")), dt_alph_gs = structure(c(0.516795865633075, 0.225903614457831,
0.575815738963532, 0.409976084728391, 0.471883602044829, 0.430416068866571,
NA, 0.556070435588508, 0.614439324116744, 0.316122233930453), label = "DT alphabet time mean", class = c("labelled",
"numeric"))), row.names = c(NA, -10L), class = "data.frame")

Not sure if this helpful (sorry I'm new to R...)

Thanks,
Cristina

[nirgrahamuk]

Thats a good step, you can improve how you share code, by formatting it for the forum, by using a three backticks, to open and close code formatting segments.

```
like this
```

I ran the following based on what you provided

dat <- structure(list(cognitive_status = structure(c(
  2L, 2L, 1L, 2L,
  1L, 1L, 2L, 1L, 2L, 2L
), .Label = c(
  "No cognitive impairment",
  "MCI"
), label = "Cognitive status group", class = c(
  "labelled",
  "factor"
)), dt_alph_gs = structure(c(
  0.516795865633075, 0.225903614457831,
  0.575815738963532, 0.409976084728391, 0.471883602044829, 0.430416068866571,
  NA, 0.556070435588508, 0.614439324116744, 0.316122233930453
), label = "DT alphabet time mean", class = c(
  "labelled",
  "numeric"
))), row.names = c(NA, -10L), class = "data.frame")

library(tidyverse)

dat %>%
  group_by(cognitive_status) %>%
  summarize(medn = median(dt_alph_gs, na.rm = T))

This did not give an error, but a result

# A tibble: 2 x 2
  cognitive_status         medn
  <fct>                   <dbl>
1 No cognitive impairment 0.514
2 MCI                     0.410

when you run what I run, do you get this same result, or an error ?

[tinaR]

@nirgrahamuk

dat <- structure(list(cognitive_status = structure(c(
  2L, 2L, 1L, 2L,
  1L, 1L, 2L, 1L, 2L, 2L
), .Label = c(
  "No cognitive impairment",
  "MCI"
), label = "Cognitive status group", class = c(
  "labelled",
  "factor"
)), dt_alph_gs = structure(c(
  0.516795865633075, 0.225903614457831,
  0.575815738963532, 0.409976084728391, 0.471883602044829, 0.430416068866571,
  NA, 0.556070435588508, 0.614439324116744, 0.316122233930453
), label = "DT alphabet time mean", class = c(
  "labelled",
  "numeric"
))), row.names = c(NA, -10L), class = "data.frame")

library(tidyverse)

dat %>%
  group_by(cognitive_status) %>%
  summarize(medn = median(dt_alph_gs, na.rm = T))

Yes, I get the same error as before..

[nirgrahamuk]

Thanks,
so can you tell me what the result is for you when you do

packageVersion("dplyr")

(I'm thinking it might not hurt to upgrade your dplyr version if its somewhat old)