Pick the top n values from the head or tail of a vector.

Source: R/in_top.R

Pick the top n values from the head or tail of a vector.

in_top(x, n = 1L)

top(x, n = 1L)

Arguments

x

An atomic vector.
n

A single integer. Doubles are silently coerced to integer.

Value

  • top() returns a vector of the same type as the input.

  • in_top() returns a logical vector.

See also

Other general functions to pick or drop rows of a dataframe: pick_recensus, pick_top

Examples


# Pick from the head
top(1:3)
#> [1] 1
# Same
top(1:3, 1L)
#> [1] 1

# Pick from the tail
top(1:3, -2L)
#> [1] 2 3

# Useful for filtering
in_top(1:3)
#> [1]  TRUE FALSE FALSE
in_top(1:3, -1L)
#> [1] FALSE FALSE  TRUE

subset(mtcars, in_top(cyl))
#>                 mpg cyl  disp  hp drat    wt  qsec vs am gear carb
#> Datsun 710     22.8   4 108.0  93 3.85 2.320 18.61  1  1    4    1
#> Merc 240D      24.4   4 146.7  62 3.69 3.190 20.00  1  0    4    2
#> Merc 230       22.8   4 140.8  95 3.92 3.150 22.90  1  0    4    2
#> Fiat 128       32.4   4  78.7  66 4.08 2.200 19.47  1  1    4    1
#> Honda Civic    30.4   4  75.7  52 4.93 1.615 18.52  1  1    4    2
#> Toyota Corolla 33.9   4  71.1  65 4.22 1.835 19.90  1  1    4    1
#> Toyota Corona  21.5   4 120.1  97 3.70 2.465 20.01  1  0    3    1
#> Fiat X1-9      27.3   4  79.0  66 4.08 1.935 18.90  1  1    4    1
#> Porsche 914-2  26.0   4 120.3  91 4.43 2.140 16.70  0  1    5    2
#> Lotus Europa   30.4   4  95.1 113 3.77 1.513 16.90  1  1    5    2
#> Volvo 142E     21.4   4 121.0 109 4.11 2.780 18.60  1  1    4    2

subset(mtcars, in_top(cyl) & in_top(carb))
#>                 mpg cyl  disp hp drat    wt  qsec vs am gear carb
#> Datsun 710     22.8   4 108.0 93 3.85 2.320 18.61  1  1    4    1
#> Fiat 128       32.4   4  78.7 66 4.08 2.200 19.47  1  1    4    1
#> Toyota Corolla 33.9   4  71.1 65 4.22 1.835 19.90  1  1    4    1
#> Toyota Corona  21.5   4 120.1 97 3.70 2.465 20.01  1  0    3    1
#> Fiat X1-9      27.3   4  79.0 66 4.08 1.935 18.90  1  1    4    1

subset(mtcars, in_top(cyl, -2L))
#>                      mpg cyl  disp  hp drat    wt  qsec vs am gear carb
#> Mazda RX4           21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4
#> Mazda RX4 Wag       21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4
#> Hornet 4 Drive      21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1
#> Hornet Sportabout   18.7   8 360.0 175 3.15 3.440 17.02  0  0    3    2
#> Valiant             18.1   6 225.0 105 2.76 3.460 20.22  1  0    3    1
#> Duster 360          14.3   8 360.0 245 3.21 3.570 15.84  0  0    3    4
#> Merc 280            19.2   6 167.6 123 3.92 3.440 18.30  1  0    4    4
#> Merc 280C           17.8   6 167.6 123 3.92 3.440 18.90  1  0    4    4
#> Merc 450SE          16.4   8 275.8 180 3.07 4.070 17.40  0  0    3    3
#> Merc 450SL          17.3   8 275.8 180 3.07 3.730 17.60  0  0    3    3
#> Merc 450SLC         15.2   8 275.8 180 3.07 3.780 18.00  0  0    3    3
#> Cadillac Fleetwood  10.4   8 472.0 205 2.93 5.250 17.98  0  0    3    4
#> Lincoln Continental 10.4   8 460.0 215 3.00 5.424 17.82  0  0    3    4
#> Chrysler Imperial   14.7   8 440.0 230 3.23 5.345 17.42  0  0    3    4
#> Dodge Challenger    15.5   8 318.0 150 2.76 3.520 16.87  0  0    3    2
#> AMC Javelin         15.2   8 304.0 150 3.15 3.435 17.30  0  0    3    2
#> Camaro Z28          13.3   8 350.0 245 3.73 3.840 15.41  0  0    3    4
#> Pontiac Firebird    19.2   8 400.0 175 3.08 3.845 17.05  0  0    3    2
#> Ford Pantera L      15.8   8 351.0 264 4.22 3.170 14.50  0  1    5    4
#> Ferrari Dino        19.7   6 145.0 175 3.62 2.770 15.50  0  1    5    6
#> Maserati Bora       15.0   8 301.0 335 3.54 3.570 14.60  0  1    5    8

# Careful: Remember that `FALSE` evaluates to 0
lgl <- c(TRUE, FALSE, TRUE)
int <- as.integer(lgl)
int
#> [1] 1 0 1

top(lgl)
#> [1] FALSE
top(int)
#> [1] 0

top(lgl, -1)
#> [1] TRUE
top(int, -1)
#> [1] 1