spine {vcd} | R Documentation

## Spine Plots and Spinograms

### Description

Spine plots are a special cases of mosaic plots, and can be seen as a generalization of stacked (or highlighted) bar plots. Analogously, spinograms are an extension of histograms.

### Usage

    spine(x, ...)
    ## Default S3 method:
    spine(x, y = NULL,
      breaks = NULL, ylab_tol = 0.05, off = NULL,
      main = "", xlab = NULL, ylab = NULL, margins = c(5.1, 4.1, 4.1, 3.1),
      gp = gpar(), name = "spineplot", newpage = TRUE, pop = TRUE,
      ...)
    ## S3 method for class 'formula':
    spine(formula, data = list(),
      breaks = NULL, ylab_tol = 0.05, off = NULL,
      main = "", xlab = NULL, ylab = NULL, margins = c(5.1, 4.1, 4.1, 3.1),
      gp = gpar(), name = "spineplot", newpage = TRUE, pop = TRUE,
      ...)

### Arguments

`x` | an object, the default method expects either a single variable (interpreted to be the explanatory variable) or a 2-way table. See details.
`y` | a `"factor"` interpreted to be the dependent variable
`formula` | a `"formula"` of type `y ~ x` with a single dependent `"factor"` and a single explanatory variable.
`data` | an optional data frame.
`breaks` | if the explantory variable is numeric, this controls how it is discretized. `breaks` is passed to `hist` and can be a list of arguments.
`ylab_tol` | convenience tolerance parameter for y-axis annotation. If the distance between two labels drops under this threshold, they are plotted equidistantly.
`off` | vertical offset between the bars (in per cent). It is fixed to `0` for spinograms and defaults to `2` for spine plots.
`main, xlab, ylab` | character strings for annotation
`margins` | margins when calling `plotViewport`
`gp` | a `"gpar"` object controlling the grid graphical parameters of the rectangles. It should specify in particular a vector of `fill` colors of the same length as `levels(y)`. The default is to call `gray.colors`.
`name` | name of the plotting viewport.
`newpage` | logical. Should `grid.newpage` be called before plotting?
`pop` | logical. Should the viewport created be popped?
`...` | additional arguments passed to `plotViewport`.

### Details

`spine` creates either a spinogram or a spine plot. It can be called via `spine(x, y)` or `spine(y ~ x)` where `y` is interpreted to be the dependent variable (and has to be categorical) and `x` the explanatory variable. `x` can be either categorical (then a spine plot is created) or numerical (then a spinogram is plotted). Additionally, `spine` can also be called with only a single argument which then has to be a 2-way table, interpreted to correspond to `table(x, y)`.

Spine plots are a generalization of stacked bar plots where not the heights but the widths of the bars corresponds to the relative frequencies of `x`. The heights of the bars then correspond to the conditional relative frequencies of `y` in every `x` group. This is a special case of a mosaic plot with specific spacing and shading.

Analogously, spinograms extend stacked histograms. As for the histogram, `x` is first discretized (using `hist`) and then for the discretized data a spine plot is created.

### Value

The table visualized is returned invisibly.

### Author(s)

Achim Zeileis Achim.Zeileis@R-project.org

### References

Hummel, J. (1996), Linked bar charts: Analysing categorical data graphically. Computational Statistics, 11, 23–33.

Hofmann, H., Theus, M. (2005), Interactive graphics for visualizing conditional distributions, Unpublished Manuscript.

### See Also

`cd_plot`, `mosaic`, `hist`

### Examples

    ## Arthritis data (dependence on a categorical variable)
    data("Arthritis")
    (spine(Improved ~ Treatment, data = Arthritis))

    ## Arthritis data (dependence on a numerical variable)
    (spine(Improved ~ Age, data = Arthritis, breaks = 5))
    (spine(Improved ~ Age, data = Arthritis, breaks = quantile(Arthritis$Age)))
    (spine(Improved ~ Age, data = Arthritis, breaks = "Scott"))

    ## Space shuttle data (dependence on a numerical variable)
    data("SpaceShuttle")
    (spine(Fail ~ Temperature, data = SpaceShuttle, breaks = 3))

[Package vcd version 0.9-6 Index]