Produce or manipulate a flat contingency table using formula notation.
## S3 method for class 'formula' ftable(formula, data = NULL, subset, na.action, ...)
a formula object with both left and right hand sides specifying the column and row variables of the flat table.
a data frame, list or environment (or similar: see
an optional vector specifying a subset of observations
to be used.
a function which indicates what should happen when
the data contain
further arguments to the default ftable method may also
be passed as arguments, see
This is a method of the generic function
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
. may be used once in the formula to indicate
inclusion of all the remaining variables.
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
should be a data frame or matrix, list or environment containing the
variables to be cross-tabulated. In this case,
applied to the data to handle missing values, and, after possibly
selecting a subset of the data as specified by the
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
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.
Titanic x <- ftable(Survived ~ ., data = Titanic) x ftable(Sex ~ Class + Age, data = x)
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