memisc: genTable – R documentation

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genTable

Generic Tables and Data Frames of Descriptive Statistics

Description

genTable creates a table of arbitrary summaries conditional on given values of independent variables given by a formula.

Aggregate does the same, but returns a data.frame instead.

fapply is a generic function that dispatches on its data argument. It is called internally by Aggregate and genTable. Methods for this function can be used to adapt Aggregate and genTable to data sources other than data frames.

Usage

Aggregate(formula, data=parent.frame(), subset=NULL,
          names=NULL, addFreq=TRUE, drop = TRUE, as.vars=1,
          ...)

genTable(formula, data=parent.frame(), subset=NULL,
         names=NULL, addFreq=TRUE,...)

Arguments

`formula`	a formula. The right hand side includes one or more grouping variables separated by '+'. These may be factors, numeric, or character vectors. The left hand side may be empty, a numerical variable, a factor, or an expression. See details below.
`data`	an environment or data frame or an object coercable into a data frame.
`subset`	an optional vector specifying a subset of observations to be used.
`names`	an optional character vector giving names to the result(s) yielded by the expression on the left hand side of `formula`. This argument may be redundant if the left hand side results in is a named vector. (See the example below.)
`addFreq`	a logical value. If `TRUE` and `data` is a table or a data frame with a variable named "Freq", a call to `table`, `Table`, `percent`, or `nvalid` is supplied by an additional argument `Freq` and a call to `table` is translated into a call to `Table`.
`drop`	a logical value. If `TRUE`, empty groups (i.e. when there are no observations in the aggregated data frame that contain the defining combination of values or factor levels of the conditioning variables in `by`) are dropped from the result of `Aggregate`. Otherwise, result are filled with `NA`, where appropriate.
`as.vars`	an integer; relevant only if the left hand side of the formula returns an array or a matrix - which dimension (rows, columns, or layers etc.) will transformed to variables? Defaults to columns in case of matrices and to the highest dimensional extend in case of arrays.
`...`	further arguments, passed to methods or ignored.

Details

If an expression is given as left hand side of the formula, its value is computed for any combination of values of the values on the right hand side. If the right hand side is a dot, then all variables in data are added to the right hand side of the formula.

If no expression is given as left hand side, then the frequency counts for the respective value combinations of the right hand variables are computed.

If a single factor is on the left hand side, then the left hand side is translated into an appropriate call to table(). Note that also in this case addFreq takes effect.

If a single numeric variable is on the left hand side, frequency counts weighted by this variable are computed. In these cases, genTable is equivalent to xtabs and Aggregate is equivalent to as.data.frame(xtabs(...)).

Value

Aggregate results in a data frame with conditional summaries and unique value combinations of conditioning variables.

genTable returns a table, that is, an array with class "table".

Examples

ex.data <- expand.grid(mu=c(0,100),sigma=c(1,10))[rep(1:4,rep(100,4)),]
ex.data <- within(ex.data,
                  x<-rnorm(
                    n=nrow(ex.data),
                    mean=mu,
                    sd=sigma
                    )
                  )

Aggregate(~mu+sigma,data=ex.data)
Aggregate(mean(x)~mu+sigma,data=ex.data)
Aggregate(mean(x)~mu+sigma,data=ex.data,name="Average")
Aggregate(c(mean(x),sd(x))~mu+sigma,data=ex.data)
Aggregate(c(Mean=mean(x),StDev=sd(x),N=length(x))~mu+sigma,data=ex.data)
genTable(c(Mean=mean(x),StDev=sd(x),N=length(x))~mu+sigma,data=ex.data)

Aggregate(table(Admit)~.,data=UCBAdmissions)
Aggregate(Table(Admit,Freq)~.,data=UCBAdmissions)
Aggregate(Admit~.,data=UCBAdmissions)
Aggregate(percent(Admit)~.,data=UCBAdmissions)
Aggregate(percent(Admit)~Gender,data=UCBAdmissions)
Aggregate(percent(Admit)~Dept,data=UCBAdmissions)
Aggregate(percent(Gender)~Dept,data=UCBAdmissions)
Aggregate(percent(Admit)~Dept,data=UCBAdmissions,Gender=="Female")
genTable(percent(Admit)~Dept,data=UCBAdmissions,Gender=="Female")

memisc

Management of Survey Data and Presentation of Analysis Results

v0.99.27.3

GPL-2

Authors

Martin Elff (with contributions from Christopher N. Lawrence, Dave Atkins, Jason W. Morgan, Achim Zeileis)

Initial release

2020-11-18