R: Tables of summary statistics

stat.table {Epi} | R Documentation

## Tables of summary statistics

### Description

`stat.table` creates tabular summaries of the data, using a limited set of functions. A list of index variables is used to cross-classify summary statistics. It does NOT work inside `with()`!

### Usage

    stat.table(index, contents = count(), data, margins = FALSE)
    ## S3 method for class 'stat.table'
    print(x, width=7, digits,...)

### Arguments

`index` | A factor, or list of factors, used for cross-classification. If the list is named, then the names will be used when printing the table. This feature can be used to give informative labels to the variables.
`contents` | A function call, or list of function calls. Only a limited set of functions may be called (See Details below). If the list is named, then the names will be used when printing the table.
`data` | an optional data frame containing the variables to be tabulated. If this is omitted, the variables will be searched for in the calling environment.
`margins` | a logical scalar or vector indicating which marginal tables are to be calculated. If a vector, it should be the same length as the `index` argument: values corresponding to `TRUE` will be retained in marginal tables.
`x` | an object of class `stat.table`.
`width` | a scalar giving the minimum column width when printing.
`digits` | a scalar, or named vector, giving the number of digits to print after the decimal point. If a named vector is used, the names should correspond to one of the permitted functions (See Details below) and all results obtained with that function will be printed with the same precision.
`...` | further arguments passed to other print methods.

### Details

This function is similar to `tapply`, with some enhancements: multiple summaries of multiple variables may be mixed in the same table; marginal tables may be calculated; columns and rows may be given informative labels; pretty printing may be controlled by the associated print method.

This function is not a replacement for `tapply` as it also has some limitations. The only functions that may be used in the `contents` argument are: `count`, `mean`, `weighted.mean`, `sum`, `quantile`, `median`, `IQR`, `max`, `min`, `ratio`, `percent`, and `sd`.

The `count()` function, which is the default, simply creates a contingency table of counts. The other functions are applied to each cell created by combinations of the `index` variables.

### Value

An object of class `stat.table`, which is a multi-dimensional array. A print method is available to create formatted one-way and two-way tables.

### Note

The permitted functions in the contents list are defined inside `stat.table`. They have the same interface as the functions callable from the command line, except for two differences. If there is an argument `na.rm` then its default value is always `TRUE`. A second difference is that the `quantile` function can only produce a single quantile in each call.

### Author(s)

Martyn Plummer

### See Also

`table`, `tapply`, `mean`, `weighted.mean`, `sum`, `quantile`, `median`, `IQR`, `max`, `min`, `ratio`, `percent`, `count`, `sd`.

### Examples

    data(warpbreaks)
    # A one-way table
    stat.table(tension,list(count(),mean(breaks)),data=warpbreaks)
    # The same table with informative labels
    stat.table(index=list("Tension level"=tension),list(N=count(),
               "mean number of breaks"=mean(breaks)),data=warpbreaks)

    # A two-way table
    stat.table(index=list(tension,wool),mean(breaks),data=warpbreaks)
    # The same table with margins over tension, but not wool
    stat.table(index=list(tension,wool),mean(breaks),data=warpbreaks,
               margins=c(TRUE, FALSE))

    # A table of column percentages
    stat.table(list(tension,wool), percent(tension), data=warpbreaks)
    # Cell percentages, with margins
    stat.table(list(tension,wool),percent(tension,wool), margin=TRUE,
               data=warpbreaks)

    # A table with multiple statistics
    # Note how each statistic has its own default precision
    a <- stat.table(index=list(wool,tension),
                    contents=list(count(),mean(breaks),percent (wool)),
                    data=warpbreaks)
    print(a)
    # Print the percentages rounded to the nearest integer
    print(a, digits=c(percent=0))

[Package Epi version 2.47 Index]