hist {graphics}  R Documentation 
The generic function hist
computes a histogram of the given
data values. If plot=TRUE
, the resulting object of
class "histogram"
is plotted by
plot.histogram
, before it is returned.
hist(x, ...) ## Default S3 method: hist(x, breaks = "Sturges", freq = NULL, probability = !freq, include.lowest = TRUE, right = TRUE, density = NULL, angle = 45, col = NULL, border = NULL, main = paste("Histogram of" , xname), xlim = range(breaks), ylim = NULL, xlab = xname, ylab, axes = TRUE, plot = TRUE, labels = FALSE, nclass = NULL, ...)
x 
a vector of values for which the histogram is desired. 
breaks 
one of:

freq 
logical; if TRUE , the histogram graphic is a
representation of frequencies, the counts component of
the result; if FALSE , probability densities, component
density , are plotted (so that the histogram has a total area
of one). Defaults to TRUE if and only if breaks are
equidistant (and probability is not specified). 
probability 
an alias for !freq , for S compatibility. 
include.lowest 
logical; if TRUE , an x[i] equal to
the breaks value will be included in the first (or last, for
right = FALSE ) bar. This will be ignored (with a warning)
unless breaks is a vector. 
right 
logical; if TRUE , the histograms cells are
rightclosed (left open) intervals. 
density 
the density of shading lines, in lines per inch.
The default value of NULL means that no shading lines
are drawn. Nonpositive values of density also inhibit the
drawing of shading lines. 
angle 
the slope of shading lines, given as an angle in degrees (counterclockwise). 
col 
a colour to be used to fill the bars.
The default of NULL yields unfilled bars. 
border 
the color of the border around the bars. The default is to use the standard foreground color. 
main, xlab, ylab 
these arguments to title have useful
defaults here. 
xlim, ylim 
the range of x and y values with sensible defaults.
Note that xlim is not used to define the histogram (breaks),
but only for plotting (when plot = TRUE ). 
axes 
logical. If TRUE (default), axes are draw if the
plot is drawn. 
plot 
logical. If TRUE (default), a histogram is
plotted, otherwise a list of breaks and counts is returned. In the
latter case, a warning is used if (typically graphical) arguments
are specified that only apply to the plot = TRUE case. 
labels 
logical or character. Additionally draw labels on top
of bars, if not FALSE ; see plot.histogram . 
nclass 
numeric (integer). For S(PLUS) compatibility only,
nclass is equivalent to breaks for a scalar or
character argument. 
... 
further graphical parameters passed to
plot.histogram and their to title and
axis (if plot=TRUE ). 
The definition of “histogram” differs by source (with
countryspecific biases). R's default with equispaced breaks (also
the default) is to plot the counts in the cells defined by
breaks
. Thus the height of a rectangle is proportional to
the number of points falling into the cell, as is the area
provided the breaks are equallyspaced.
The default with nonequispaced breaks is to give a plot of area one, in which the area of the rectangles is the fraction of the data points falling in the cells.
If right = TRUE
(default), the histogram cells are intervals
of the form (a, b]
, i.e., they include their righthand endpoint,
but not their left one, with the exception of the first cell when
include.lowest
is TRUE
.
For right = FALSE
, the intervals are of the form [a, b)
,
and include.lowest
really has the meaning of
“include highest”.
A numerical tolerance of 1e7 times the median bin size is applied when counting entries on the edges of bins.
The default for breaks
is "Sturges"
: see
nclass.Sturges
. Other names for which algorithms
are supplied are "Scott"
and "FD"
/
"FreedmanDiaconis"
(with corresponding functions
nclass.scott
and nclass.FD
).
Case is ignored and partial matching is used.
Alternatively, a function can be supplied which
will compute the intended number of breaks as a function of x
.
an object of class "histogram"
which is a list with components:
breaks 
the n+1 cell boundaries (= breaks if that
was a vector). 
counts 
n integers; for each cell, the number of
x[] inside. 
density 
values f^(x[i]), as estimated
density values. If all(diff(breaks) == 1) , they are the
relative frequencies counts/n and in general satisfy
sum[i; f^(x[i])
(b[i+1]b[i])] = 1, where b[i] = breaks[i] . 
intensities 
same as density . Deprecated, but retained
for compatibility. 
mids 
the n cell midpoints. 
xname 
a character string with the actual x argument name. 
equidist 
logical, indicating if the distances between
breaks are all the same. 
The resulting value does not depend on the values of
the arguments freq
(or probability
)
or plot
. This is intentionally different from S.
Prior to R 1.7.0, the element breaks
of the result was
adjusted for numerical tolerances. The nominal values are now
returned even though tolerances are still used when counting.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
Venables, W. N. and Ripley. B. D. (2002) Modern Applied Statistics with S. Springer.
nclass.Sturges
, stem
,
density
, truehist
in package MASS.
Typical plots with vertical bars are not histograms. Consider
barplot
or plot(*, type = "h")
for such bar plots.
op < par(mfrow=c(2, 2)) hist(islands) utils::str(hist(islands, col="gray", labels = TRUE)) hist(sqrt(islands), br = 12, col="lightblue", border="pink") ## For nonequidistant breaks, counts should NOT be graphed unscaled: r < hist(sqrt(islands), br = c(4*0:5, 10*3:5, 70, 100, 140), col='blue1') text(r$mids, r$density, r$counts, adj=c(.5, .5), col='blue3') sapply(r[2:3], sum) sum(r$density * diff(r$breaks)) # == 1 lines(r, lty = 3, border = "purple") # > lines.histogram(*) par(op) utils::str(hist(islands, br=12, plot= FALSE)) #> 10 (~= 12) breaks utils::str(hist(islands, br=c(12,20,36,80,200,1000,17000), plot = FALSE)) hist(islands, br=c(12,20,36,80,200,1000,17000), freq = TRUE, main = "WRONG histogram") # and warning set.seed(14) x < rchisq(100, df = 4) ## Comparing data with a model distribution should be done with qqplot()! qqplot(x, qchisq(ppoints(x), df = 4)); abline(0,1, col = 2, lty = 2) ## if you really insist on using hist() ... : hist(x, freq = FALSE, ylim = c(0, 0.2)) curve(dchisq(x, df = 4), col = 2, lty = 2, lwd = 2, add = TRUE)