gsummary {nlme}  R Documentation 
Summarize by Groups
Description
Provide a summary of the variables in a data frame by groups of rows.
This is most useful with a groupedData
object to examine the
variables by group.
Usage
gsummary(object, FUN, omitGroupingFactor, form, level,
groups, invariantsOnly, ...)
Arguments
object 
an object to be summarized  usually a groupedData
object or a data.frame .

FUN 
an optional summary function or a list of summary functions
to be applied to each variable in the frame. The function or
functions are applied only to variables in object that vary
within the groups defined by groups . Invariant variables are
always summarized by group using the unique value that they assume
within that group. If FUN is a single
function it will be applied to each noninvariant variable by group
to produce the summary for that variable. If FUN is a list of
functions, the names in the list should designate classes of
variables in the frame such as ordered , factor , or
numeric . The indicated function will be applied to any
noninvariant variables of that class. The default functions to be
used are mean for numeric factors, and Mode for both
factor and ordered . The Mode function, defined
internally in gsummary , returns the modal or most popular
value of the variable. It is different from the mode function
that returns the Slanguage mode of the variable.

omitGroupingFactor 
an optional logical value. When TRUE
the grouping factor itself will be omitted from the groupwise
summary but the levels of the grouping factor will continue to be
used as the row names for the data frame that is produced by the
summary. Defaults to FALSE .

form 
an optional onesided formula that defines the groups.
When this formula is given, the righthand side is evaluated in
object , converted to a factor if necessary, and the unique
levels are used to define the groups. Defaults to
formula(object) .

level 
an optional positive integer giving the level of grouping
to be used in an object with multiple nested grouping levels.
Defaults to the highest or innermost level of grouping.

groups 
an optional factor that will be used to split the
rows into groups. Defaults to getGroups(object, form, level) .

invariantsOnly 
an optional logical value. When TRUE only
those covariates that are invariant within each group will be
summarized. The summary value for the group is always the unique
value taken on by that covariate within the group. The columns in
the summary are of the same class as the corresponding columns in
object . By definition, the grouping factor itself must be an
invariant. When combined with omitGroupingFactor = TRUE ,
this option can be used to discover is there are invariant covariates
in the data frame. Defaults to FALSE .

... 
optional additional arguments to the summary functions
that are invoked on the variables by group. Often it is helpful to
specify na.rm = TRUE .

Value
A data.frame
with one row for each level of the grouping
factor. The number of columns is at most the number of columns in
object
.
Author(s)
JosÃ© Pinheiro and Douglas Bates bates@stat.wisc.edu
References
Pinheiro, J.C., and Bates, D.M. (2000) "MixedEffects Models
in S and SPLUS", Springer.
See Also
summary
, groupedData
,
getGroups
Examples
gsummary(Orthodont) # default summary by Subject
## gsummary with invariantsOnly = TRUE and omitGroupingFactor = TRUE
## determines whether there are covariates like Sex that are invariant
## within the repeated observations on the same Subject.
gsummary(Orthodont, inv = TRUE, omit = TRUE)
[Package
nlme version 3.1131
Index]