This operator extracts or sets attributes for regular objects and S4 fields for S4 objects.
Examples
# Unlike `@`, this operator extracts attributes for any kind of
# objects:
factor(1:3) %@% "levels"
#> [1] "1" "2" "3"
mtcars %@% class
#> [1] "data.frame"
mtcars %@% class <- NULL
mtcars
#> $mpg
#> [1] 21.0 21.0 22.8 21.4 18.7 18.1 14.3 24.4 22.8 19.2 17.8 16.4 17.3 15.2
#> [15] 10.4 10.4 14.7 32.4 30.4 33.9 21.5 15.5 15.2 13.3 19.2 27.3 26.0 30.4
#> [29] 15.8 19.7 15.0 21.4
#>
#> $cyl
#> [1] 6 6 4 6 8 6 8 4 4 6 6 8 8 8 8 8 8 4 4 4 4 8 8 8 8 4 4 4 8 6 8 4
#>
#> $disp
#> [1] 160.0 160.0 108.0 258.0 360.0 225.0 360.0 146.7 140.8 167.6 167.6
#> [12] 275.8 275.8 275.8 472.0 460.0 440.0 78.7 75.7 71.1 120.1 318.0
#> [23] 304.0 350.0 400.0 79.0 120.3 95.1 351.0 145.0 301.0 121.0
#>
#> $hp
#> [1] 110 110 93 110 175 105 245 62 95 123 123 180 180 180 205 215 230
#> [18] 66 52 65 97 150 150 245 175 66 91 113 264 175 335 109
#>
#> $drat
#> [1] 3.90 3.90 3.85 3.08 3.15 2.76 3.21 3.69 3.92 3.92 3.92 3.07 3.07 3.07
#> [15] 2.93 3.00 3.23 4.08 4.93 4.22 3.70 2.76 3.15 3.73 3.08 4.08 4.43 3.77
#> [29] 4.22 3.62 3.54 4.11
#>
#> $wt
#> [1] 2.620 2.875 2.320 3.215 3.440 3.460 3.570 3.190 3.150 3.440 3.440
#> [12] 4.070 3.730 3.780 5.250 5.424 5.345 2.200 1.615 1.835 2.465 3.520
#> [23] 3.435 3.840 3.845 1.935 2.140 1.513 3.170 2.770 3.570 2.780
#>
#> $qsec
#> [1] 16.46 17.02 18.61 19.44 17.02 20.22 15.84 20.00 22.90 18.30 18.90
#> [12] 17.40 17.60 18.00 17.98 17.82 17.42 19.47 18.52 19.90 20.01 16.87
#> [23] 17.30 15.41 17.05 18.90 16.70 16.90 14.50 15.50 14.60 18.60
#>
#> $vs
#> [1] 0 0 1 1 0 1 0 1 1 1 1 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 0 1 0 0 0 1
#>
#> $am
#> [1] 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0 1 1 1 1 1 1 1
#>
#> $gear
#> [1] 4 4 4 3 3 3 3 4 4 4 4 3 3 3 3 3 3 4 4 4 3 3 3 3 3 4 5 5 5 5 5 4
#>
#> $carb
#> [1] 4 4 1 1 2 1 4 2 2 4 4 3 3 3 4 4 4 1 2 1 1 2 2 4 2 1 2 2 4 6 8 2
#>
#> attr(,"row.names")
#> [1] "Mazda RX4" "Mazda RX4 Wag" "Datsun 710"
#> [4] "Hornet 4 Drive" "Hornet Sportabout" "Valiant"
#> [7] "Duster 360" "Merc 240D" "Merc 230"
#> [10] "Merc 280" "Merc 280C" "Merc 450SE"
#> [13] "Merc 450SL" "Merc 450SLC" "Cadillac Fleetwood"
#> [16] "Lincoln Continental" "Chrysler Imperial" "Fiat 128"
#> [19] "Honda Civic" "Toyota Corolla" "Toyota Corona"
#> [22] "Dodge Challenger" "AMC Javelin" "Camaro Z28"
#> [25] "Pontiac Firebird" "Fiat X1-9" "Porsche 914-2"
#> [28] "Lotus Europa" "Ford Pantera L" "Ferrari Dino"
#> [31] "Maserati Bora" "Volvo 142E"
# It also works on S4 objects:
.Person <- setClass("Person", slots = c(name = "character", species = "character"))
fievel <- .Person(name = "Fievel", species = "mouse")
fievel %@% name
#> [1] "Fievel"