Inconsistency using subsetting vs dplyr::filter

Question

I have a data-frame which gives gives different results, depending on the filtering method used.. see screen shot below, which seems weird. Any thoughts on why this might be?

Answer 1

Could be the presence of NAs in the data?

library(tidyverse)

df <- tibble(x = factor(rep(c(1:3, NA), 5))) # 5 x 2

df |> filter(x == 2)
#> # A tibble: 5 × 1
#>   x    
#>   <fct>
#> 1 2    
#> 2 2    
#> 3 2    
#> 4 2    
#> 5 2
df[df$x == 2, ]
#> # A tibble: 10 × 1
#>    x    
#>    <fct>
#>  1 2    
#>  2 <NA> 
#>  3 2    
#>  4 <NA> 
#>  5 2    
#>  6 <NA> 
#>  7 2    
#>  8 <NA> 
#>  9 2    
#> 10 <NA>

^{Created on 2024-04-18 with reprex v2.1.0}

This is noted at the top of the ?dplyr::filter help page:

Note that when a condition evaluates to NA the row will be dropped, unlike base subsetting with [.