oa.design {DoE.base} | R Documentation |
Function for accessing orthogonal arrays
oa.design(ID=NULL, nruns=NULL, nfactors=NULL, nlevels=NULL, factor.names = if (!is.null(nfactors)) { if (nfactors <= 50) Letters[1:nfactors] else paste("F", 1:nfactors, sep = "")} else NULL, columns=NULL, replications=1, repeat.only=FALSE, randomize=TRUE, seed=NULL, min.residual.df=0) origin(ID) comment(ID) oacat oa
ID |
name of the orthogonal array design to be used;
available names can be looked at via oacat$name ;
users can also specify names of their own designs here (cf. details).
ID must be of class oa .
If omitted, ID is automatically determined based on nlevels
or factor.names . |
nruns |
number of runs, can be omitted if obvious from ID or if
the smallest possible array is to be found |
nfactors |
number of factors;
only needed if nlevels is a single number and
factor.names is omitted;
can otherwise determined from length of factor.names ,
nlevels or column |
nlevels |
number(s) of levels, vector with nfactors entries or single number;
can be omitted, if obvious from factor.names or if ID
and columns are given or if all columns of ID are to be used;
can be a single number if nfactors is known directly or as length of
factor.names |
factor.names |
like in FrF2 |
columns |
vector of column numbers referring to columns of design ID ;
must not be specified, if ID is omitted;
the entries assign columns of the array to the factors |
replications |
the number of replications of the array,
the setting of repeat.only determines, whether these are real replications
or repeated measurements only. Note that replications are not considered for
accomodation of min.residual.df residual degrees of freedom,
unless a full factorial is used. |
repeat.only |
default FALSE implies real replications, TRUE implies repeated measurements only |
randomize |
logical indicating whether the run order is to be randomized ? |
seed |
integer seed for the random number generator |
min.residual.df |
minimum number of residual degrees of freedom |
Function oa.design
assigns factors to the columns of orthogonal arrays that are
available within package DoE.wrapper. The available arrays and their properties are listed in the
data frame oacat
. The design names also indicate the number of runs and the numbers of factors
for each number of levels, e.g. L18.2.1.3.7 is an 18 run design with one factor with
2 levels and seven factors with 3 levels each.
oa
is the S3 class used for orthogonal arrays. Objects of class oa
should at least have
the attribute “origin”, an attribute “comment” should be used for additional information.
Users can define their own orthogonal arrays and hand them to oa.design
with parameter ID
.
Requirements for the arrays:
Factor levels must be coded as a numbers from 1 to number of levels.
The array must be of classes oa
and matrix
.
The array should have an attribute origin
.
The array can have an attribute comment
;
this should be used for mentioning specific properties, e.g.
for the L18.2.1.3.7 that the interaction of the first two factors
can be estimated.
Users are encouraged to send additional arrays to the package maintainer.
The requirements for these are the same as listed above, with attribute origin
being a MUST in this case.
Currently, package DoE.base
contains the orthogonal arrays from Warren Kuhfelds
collection of “parent” arrays only. It is possible to combine these with each other, or
with Plackett-Burman, full or fractional factorial designs by nesting, as described
by Warren Kuhfeld. This is not currently implemented.
If no orthogonal array is found,
oa.design
returns a full factorial, replicated for enough degrees of freedom, if necessary.
Note that replications specified with option replications
are not counted in determining
residual degrees of freedom for min.resid.df
.
Default factor names are the first elements of the character vector Letters
,
or the factors position numbers preceded by capital F in case of more than 50 factors.
oa.design
returns a data frame of S3 class design
with attributes attached. Factors with numerical levels are numeric, factors with
character levels are factors. The content of the attributes in class design
depends
on the specific type of design used.
origin
and comment
return the respective attribute of the orthogonal array.
This package is currently under intensive development. Substantial changes are to be expected in the near future.
Ulrike Groemping
Hedayat, A.S., Sloane, N.J.A. and Stufken, J. (1999) Orthogonal Arrays: Theory and Applications, Springer, New York.
Kuhfeld, W. (2009). Orthogonal arrays. Website courtesy of SAS Institute http://support.sas.com/techsup/technote/ts723.html.
~~See Also FrF2
, oa.design
, pb
## smallest available array for 6 factors with 3 levels each oa.design(nfactors=6,nlevels=3) ## level combination for which only a full factorial is (currently) found oa.design(nlevels=c(4,3,3,2)) ## array requested via factor.names oa.design(factor.names=list(one=c("a","b","c"), two=c(125,275), three=c("old","new"), four=c(-1,1), five=c("min","medium","max"))) ## array requested via character factor.names and nlevels (with a little German lesson for one two three four five) oa.design(factor.names=c("eins","zwei","drei","vier","fuenf"),nlevels=c(2,2,2,3,7)) ## array requested via explicit name, Taguchi L18 oa.design(ID=L18) ## array requested via explicit name, with column selection oa.design(ID=L18.3.6.6.1,columns=c(2,3,7)) ## array requested with nruns, not very reasonable oa.design(nruns=12, nfactors=3, nlevels=2) ## array requested with min.residual.df oa.design(nfactors=3, nlevels=2, min.residual.df=12)