Extract and manipulate coefficients

Extract and manipulate coefficients of ktensor and kform objects; this using the methods of the spray package.

Functions as.spray() and nterms() are imported from spray.

Details

To see the coefficients of a kform or ktensor object, use coeffs(), which returns a disord object (this is actually spray::coeffs()). Replacement methods also use the methods of the spray package. Note that disordR discipline is enforced.

Experimental functionality for “pure” extraction and replacement is provided, following spray version 1.0-25 or above. Thus idiom such as a[abs(coeffs(a)) > 0.1] or indeed a[coeffs(a) < 1] <- 0 should work as expected.

Author

Robin K. S. Hankin

Examples

(a <- kform_general(5,2,1:10))
#> An alternating linear map from V^2 to R with V=R^5:
#>          val
#>  2 5  =    8
#>  1 5  =    7
#>  3 4  =    6
#>  2 4  =    5
#>  4 5  =   10
#>  1 4  =    4
#>  2 3  =    3
#>  1 3  =    2
#>  3 5  =    9
#>  1 2  =    1
coeffs(a) # a disord object
#> A disord object with hash 3f2a0e8670c7c27e53fa60649745f5057067487d and elements
#>  [1]  8  7  6  5 10  4  3  2  9  1
#> (in some order)
coeffs(a)[coeffs(a)%%2==1] <- 100  # replace every odd coeff with 100
a
#> An alternating linear map from V^2 to R with V=R^5:
#>          val
#>  1 2  =  100
#>  3 5  =  100
#>  1 3  =    2
#>  2 3  =  100
#>  1 4  =    4
#>  4 5  =   10
#>  2 4  =  100
#>  3 4  =    6
#>  1 5  =  100
#>  2 5  =    8

coeffs(a*0)
#> numeric(0)

a <- rform()
a[coeffs(a) < 5]         # experimental
#>            val
#>  2 4 7  =    1
#>  3 4 5  =    4
#>  4 5 6  =   -2
#>  1 4 6  =   -9
#>  1 3 5  =   -6
a[coeffs(a) > 3] <- 99   # experimental