Apply functions to elements of a cycle

Function capply() means “cycle apply” and is modelled on lapply(). It applies a function to every element in the cycles of its argument.

Usage

capply(X, fun, ...)

Arguments

X

Permutation, coerced to cycle

fun

Function to be applied to each element of X

...

Further arguments to fun()

Details

This function is just a convenience wrapper really.

Value

Returns a permutation in cycle form

Author

Robin K. S. Hankin

Note

Function allcyc() is a nice application of capply().

See also

allcyc

Examples

(x <- rperm())
#>  [1] (1274)(56)    (1372465)     (153264)      (1763254)     (137)(25)(46)
#>  [6] (1536274)     (375)         (14)(257)     (24756)       (1647325)    
#> [coerced from word form]
capply(x,range)
#>  [1] (17)(56)     (17)         (16)         (17)         (17)(25)(46)
#>  [6] (17)         (37)         (14)(27)     (27)         (17)        

capply(x,function(x){x+100})
#>  [1] (101,102,107,104)(105,106)      (101,103,107,102,104,106,105)  
#>  [3] (101,105,103,102,106,104)       (101,107,106,103,102,105,104)  
#>  [5] (101,103,107)(102,105)(104,106) (101,105,103,106,102,107,104)  
#>  [7] (103,107,105)                   (101,104)(102,105,107)         
#>  [9] (102,104,107,105,106)           (101,106,104,107,103,102,105)  

capply(x,rev)
#>  [1] (1472)(56)    (1564273)     (146235)      (1452367)     (173)(25)(46)
#>  [6] (1472635)     (357)         (14)(275)     (26574)       (1523746)    
all(is.id(capply(x,rev)*x))  # should be TRUE
#> [1] TRUE

capply(rcyc(20,5,9),sort)
#>  [1] (13479) (12468) (12346) (12389) (12367) (12346) (12456) (23579) (23459)
#> [10] (12678) (13467) (13468) (35679) (24689) (13678) (12369) (35789) (12389)
#> [19] (12578) (23679)

capply(rcyc(20,5,9),sample)  # still 5-cycles
#>  [1] (17234) (38957) (18459) (15936) (16579) (15724) (17895) (39854) (36784)
#> [10] (26897) (13862) (13259) (39746) (23946) (39586) (19745) (28594) (17938)
#> [19] (35678) (25894)


capply(cyc_len(1:9),\(x)x[x>4])
#> [1] ()      ()      ()      ()      ()      (56)    (567)   (5678)  (56789)

capply(cyc_len(1:9),\(x)x^2)
#> [1] ()                        (1,4)                    
#> [3] (1,4,9)                   (1,4,9,16)               
#> [5] (1,4,9,16,25)             (1,4,9,16,25,36)         
#> [7] (1,4,9,16,25,36,49)       (1,4,9,16,25,36,49,64)   
#> [9] (1,4,9,16,25,36,49,64,81)