R语言直方图hist函数介绍(附源文档)

R语言直方图hist的绘制

查询hist的用法

> ?hist

他的参数有下面这么多,我们介绍大多数常用的参数

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, warn.unused = TRUE, ...)

x:向量,通常是向量,也就是直方图所用到的数据。
breaks 直方图的分组 可以理解为设定直方图里面有几根柱子
main 设定名字
col 填充颜色
xlim,ylim设置x.y轴的范围
xlab,ylib设定x,y轴的名字

注:下面是源文档,其他参数有兴趣的可以自行翻译

hist {graphics}	R Documentation
Histograms
Description
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.

Usage
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, warn.unused = TRUE, ...)
Arguments
x	
a vector of values for which the histogram is desired. # 需要直方图的值的向量。

breaks	
one of:

a vector giving the breakpoints between histogram cells,#一个给出直方图单元之间断点的向量，

a function to compute the vector of breakpoints,#一个计算断点向量的函数，

a single number giving the number of cells for the histogram,#一个数字，给出直方图的细胞数量，

a character string naming an algorithm to compute the number of cells (see ‘Details’),#一个字符串命名一个算法来计算细胞的数量(见“详情”)，

a function to compute the number of cells.#计算单元数目的函数。

In the last three cases the number is a suggestion only; as the breakpoints will be set to pretty values, the number is limited to 1e6 (with a warning if it was larger). If breaks is a function, the x vector is supplied to it as the only argument (and the number of breaks is only limited by the amount of available memory).

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).
#逻辑;如果是，直方图图形是频率的表示，计数组成的结果;如果为假，则绘制概率密度、组件密度(因此直方图的总面积为1)。#当且仅当断点距离相等时，默认值为TRUE(未指定概率)。
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 histogram cells are right-closed (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. Non-positive values of density also inhibit the drawing of shading lines.

angle	
the slope of shading lines, given as an angle in degrees (counter-clockwise).

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	
main title and axis labels: these arguments to title() get “smart” defaults here, e.g., the default ylab is "Frequency" iff freq is true.

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 string. 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.

warn.unused	
logical. If plot = FALSE and warn.unused = TRUE, a warning will be issued when graphical parameters are passed to hist.default().

...	
further arguments and graphical parameters passed to plot.histogram and thence to title and axis (if plot = TRUE).

Details
The definition of histogram differs by source (with country-specific biases). R's default with equi-spaced 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 equally-spaced.

The default with non-equi-spaced 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 right-hand 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 means ‘include highest’.

A numerical tolerance of 1e-7 times the median bin size (for more than four bins, otherwise the median is substituted) is applied when counting entries on the edges of bins. This is not included in the reported breaks nor in the calculation of density.

The default for breaks is "Sturges": see nclass.Sturges. Other names for which algorithms are supplied are "Scott" and "FD" / "Freedman-Diaconis" (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 or the actual breakpoints as a function of x.

Value
an object of class "histogram" which is a list with components:

breaks	
the n+1 cell boundaries (= breaks if that was a vector). These are the nominal breaks, not with the boundary fuzz.

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].

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.

References
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.

See Also
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.

Examples
op <- par(mfrow = c(2, 2))
hist(islands)
utils::str(hist(islands, col = "gray", labels = TRUE))

hist(sqrt(islands), breaks = 12, col = "lightblue", border = "pink")
##-- For non-equidistant breaks, counts should NOT be graphed unscaled:
r <- hist(sqrt(islands), breaks = 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)

require(utils) # for str
str(hist(islands, breaks = 12, plot =  FALSE)) #-> 10 (~= 12) breaks
str(hist(islands, breaks = c(12,20,36,80,200,1000,17000), plot = FALSE))

hist(islands, breaks = c(12,20,36,80,200,1000,17000), freq = TRUE,
     main = "WRONG histogram") # and warning

## Extreme outliers; the "FD" rule would take very large number of 'breaks':
XXL <- c(1:9, c(-1,1)*1e300)
hh <- hist(XXL, "FD") # did not work in R <= 3.4.1; now gives warning
## pretty() determines how many counts are used (platform dependently!):
length(hh$breaks) ## typically 1 million -- though 1e6 was "a suggestion only"

require(stats)
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)

[Package graphics version 3.6.2 Index]