groupwise summarise is returning NA; also in minor example from the web

Question

I try to generate yearwise summary statistics as follows:

data %>%
  group_by(year) %>%
    summarise(mean.abc = mean(abc), mean.def = mean(def), sd.abc = sd(abc), sd.def = sd(def))

This code returns a row vector filled with NA in the respective columns

  mean.abc mean.def sd.abc sd.def
1       NA       NA     NA     NA

So, I tried to work this out and replicated some examples

data(mtcars)

mtcars %>%
  group_by(cyl) %>%
  summarise(mean = mean(disp))

And this script returns

      mean
1 230.7219

So, what am I doing wrong? I am loading the following packages:

loadpackage( c("foreign","haven", "tidyverse", "plyr", "stringr", "eeptools", "factoextra") )

Thanky for your support!

Answer 1

Your issue is that the summarise-function from the plyr-package does not do what you expect it to do.

See the difference between:

library(tidyverse)

mtcars %>%
  group_by(cyl) %>%
  plyr::summarise(mean = mean(disp))
#>       mean
#> 1 230.7219

and

mtcars %>%
  group_by(cyl) %>%
  dplyr::summarise(mean = mean(disp))
#> # A tibble: 3 x 2
#>     cyl  mean
#>   <dbl> <dbl>
#> 1     4  105.
#> 2     6  183.
#> 3     8  353.

Since your data seems to have missing values, this should do the trick:

   data %>% 
    group_by(year) %>% 
    dplyr::summarise(across(all_of(c('abc', 'def')),
                            .fns = list(mean = ~mean(.,na.rm=T),
                                        sd = ~sd(.,na.rm=T))))