| spineplot {graphics} | R Documentation |
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.
spineplot(x, ...)
## Default S3 method:
spineplot(x, y = NULL,
breaks = NULL, tol.ylab = 0.05, off = NULL,
col = NULL, main = "", xlab = NULL, ylab = NULL,
xaxlabels = NULL, yaxlabels = NULL,
xlim = NULL, ylim = c(0, 1), ...)
## S3 method for class 'formula':
spineplot(formula, data = list(),
breaks = NULL, tol.ylab = 0.05, off = NULL,
col = NULL, main = "", xlab = NULL, ylab = NULL,
xaxlabels = NULL, yaxlabels = NULL,
xlim = NULL, ylim = c(0, 1), ...,
subset = NULL)
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. |
tol.ylab |
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. |
col |
a vector of fill colors of the same length as levels(y).
The default is to call gray.colors. |
main, xlab, ylab |
character strings for annotation |
xaxlabels, yaxlabels |
character vectors for annotation of x and y axis.
Default to levels(y) and levels(x), respectively for the
spine plot. For xaxlabels in the spinogram, the breaks are
used. |
xlim, ylim |
the range of x and y values with sensible defaults. |
... |
additional arguments passed to rect. |
subset |
an optional vector specifying a subset of observations to be used for plotting. |
spineplot creates either a spinogram or a spine plot. It can
be called via spineplot(x, y) or spineplot(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, spineplot 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).
Both, spine plots and spinograms, are essentially mosaic plots with
special formatting of spacing and shading. Conceptually, they plot
P(y | x) against P(x). For the spine plot (where both
x and y are categorical), both quantities are approximated
by the corresponding empirical relative frequencies. For the
spinogram (where x is numerical), x is first discretized
(by caling hist with breaks argument) and then
empirical relative frequencies are taken.
Thus, spine plots can also be seen as 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. Analogously, spinograms extend stacked
histograms.
The table visualized is returned invisibly.
Achim Zeileis Achim.Zeileis@R-project.org
Friendly, M. (1994), Mosaic displays for multi-way contingency tables. Journal of the American Statistical Association, 89, 190–200.
Hartigan, J.A., and Kleiner, B. (1984), A mosaic of television ratings. The American Statistician, 38, 32–35.
Hofmann, H., Theus, M. (2005), Interactive graphics for visualizing conditional distributions, Unpublished Manuscript.
Hummel, J. (1996), Linked bar charts: Analysing categorical data graphically. Computational Statistics, 11, 23–33.
## treatment and improvement of patients with rheumatoid arthritis
treatment <- factor(rep(c(1, 2), c(43, 41)), levels = c(1, 2),
labels = c("placebo", "treated"))
improved <- factor(rep(c(1, 2, 3, 1, 2, 3), c(29, 7, 7, 13, 7, 21)),
levels = c(1, 2, 3), labels = c("none", "some", "marked"))
## (dependence on a categorical variable)
(spineplot(improved ~ treatment))
## applications and admissions by department at UC Berkeley
## (two-way tables)
(spineplot(margin.table(UCBAdmissions, c(3, 2)),
main = "Applications at UCB"))
(spineplot(margin.table(UCBAdmissions, c(3, 1)),
main = "Admissions at UCB"))
## NASA space shuttle o-ring failures
fail <- factor(c(2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1,
1, 1, 1, 2, 1, 1, 1, 1, 1),
levels = c(1, 2), labels = c("no", "yes"))
temperature <- c(53, 57, 58, 63, 66, 67, 67, 67, 68, 69, 70, 70,
70, 70, 72, 73, 75, 75, 76, 76, 78, 79, 81)
## (dependence on a numerical variable)
(spineplot(fail ~ temperature))
(spineplot(fail ~ temperature, breaks = 3))
(spineplot(fail ~ temperature, breaks = quantile(temperature)))