R: Expand a frequency table to case form

expand.dft {vcdExtra} | R Documentation

## Expand a frequency table to case form

### Description

Converts a frequency table, given either as a table object or a data frame in frequency form to a data frame representing individual observations in the table.

### Usage

    expand.dft(x, var.names = NULL, freq = "Freq", ...)

    expand.table(x, var.names = NULL, freq = "Freq", ...)

### Arguments

`x` | A table object, or a data frame in frequency form containing factors and one numeric variable representing the cell frequency for that combination of factors.
`var.names` | A list of variable names for the factors, if you wish to override those already in the table
`freq` | The name of the frequency variable in the table
`...` | Other arguments passed down to `type.convert`. In particular, pay attention to `na.strings` (default: `na.strings=NA` if there are missing cells) and `as.is` (default: `as.is=FALSE`, converting character vectors to factors).

### Details

`expand.table` is a synonym for `expand.dft`.

### Value

A data frame containing the factors in the table and as many observations as are represented by the total of the `freq` variable.

### Author(s)

Mark Schwarz

### References

Originally posted on R-Help, Jan 20, 2009, http://tolstoy.newcastle.edu.au/R/e6/help/09/01/1873.html

Friendly, M. and Meyer, D. (2016). Discrete Data Analysis with R: Visualization and Modeling Techniques for Categorical and Count Data. Boca Raton, FL: Chapman & Hall/CRC. http://ddar.datavis.ca.

### See Also

`type.convert`, `expandCategorical`

### Examples

    library(vcd)
    art <- xtabs(~Treatment + Improved, data = Arthritis)
    art
    artdf <- expand.dft(art)
    str(artdf)

    # 1D case
    (tab <- table(sample(head(letters), 20, replace=TRUE)))
    expand.table(tab, var.names="letter")

[Package vcdExtra version 0.7-1 Index]