ftable.formula {stats} | R Documentation |

## Formula Notation for Flat Contingency Tables

### Description

Produce or manipulate a flat contingency table using
formula notation.

### Usage

## S3 method for class 'formula':
ftable(formula, data = NULL, subset, na.action, ...)

### Arguments

`formula` |
a formula object with both left and right hand sides
specifying the column and row variables of the flat table. |

`data` |
a data frame, list or environment containing the variables
to be cross-tabulated, or a contingency table (see below). |

`subset` |
an optional vector specifying a subset of observations
to be used.
Ignored if `data` is a contingency table. |

`na.action` |
a function which indicates what should happen when
the data contain `NA` s.
Ignored if `data` is a contingency table. |

`...` |
further arguments to the default ftable method may also
be passed as arguments, see `ftable.default` . |

### Details

This is a method of the generic function `ftable`

.

The left and right hand side of `formula`

specify the column and
row variables, respectively, of the flat contingency table to be
created. Only the `+`

operator is allowed for combining the
variables. A `.`

may be used once in the formula to indicate
inclusion of all the “remaining” variables.

If `data`

is an object of class `"table"`

or an array with
more than 2 dimensions, it is taken as a contingency table, and hence
all entries should be nonnegative. Otherwise, if it is not a flat
contingency table (i.e., an object of class `"ftable"`

), it
should be a data frame or matrix, list or environment containing the
variables to be cross-tabulated. In this case, `na.action`

is
applied to the data to handle missing values, and, after possibly
selecting a subset of the data as specified by the `subset`

argument, a contingency table is computed from the variables.

The contingency table is then collapsed to a flat table, according to
the row and column variables specified by `formula`

.

### Value

A flat contingency table which contains the counts of each combination
of the levels of the variables, collapsed into a matrix for suitably
displaying the counts.

### See Also

`ftable`

,
`ftable.default`

;
`table`

.

### Examples

Titanic
x <- ftable(Survived ~ ., data = Titanic)
x
ftable(Sex ~ Class + Age, data = x)

[Package

*stats* version 2.2.1

Index]