饼图
饼图可由函数pie()创建
Usage
pie(x, labels = names(x), edges = 200, radius = 0.8,
clockwise = FALSE, init.angle = if(clockwise) 90 else 0,
density = NULL, angle = 45, col = NULL, border = NULL,
lty = NULL, main = NULL, ...)
Arguments
x
a vector of non-negative numerical quantities. The values in x are displayed as the areas of pie slices.
labels
one or more expressions or character strings giving names for the slices. Other objects are coerced by as.graphicsAnnot. For empty or NA (after coercion to character) labels, no label nor pointing line is drawn.
edges
the circular outline of the pie is approximated by a polygon with this many edges.
radius
the pie is drawn centered in a square box whose sides range from -1 to 1. If the character strings labeling the slices are long it may be necessary to use a smaller radius.
clockwise
logical indicating if slices are drawn clockwise or counter clockwise (i.e., mathematically positive direction), the latter is default.
init.angle
number specifying the starting angle (in degrees) for the slices. Defaults to 0 (i.e., ‘3 o'clock’) unless clockwise is true where init.angle defaults to 90 (degrees), (i.e., ‘12 o'clock’).
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 vector of colors to be used in filling or shading the slices. If missing a set of 6 pastel colours is used, unless density is specified when par("fg") is used.
border, lty
(possibly vectors) arguments passed to polygon which draws each slice.
main
an overall title for the plot.
...
graphical parameters can be given as arguments to pie. They will affect the main title and labels only.
例
pie(rep(1, 24), col = rainbow(24), radius = 0.9)
image.png
扇形图
饼图让比较各扇形的值变得困难（除非这些值被附加在标签上），为改善这种状况，我们创造了一种称为扇形图（fan.plot）的饼图变种。扇形图（Lemon& Tyagi,2009）提供了一种同时展示相对数量和相互差异的方法。在R中，扇形图是通过plotrix包中的fan.plot()函数实现的
Usage
fan.plot(x,edges=200,radius=1,col=NULL,align.at=NULL,max.span=NULL,
labels=NULL,labelpos=NULL,label.radius=1.2,align="left",shrink=0.02,
main="",ticks=NULL,include.sumx=FALSE,...)
Arguments
x
Vector of numbers.
edges
The number of edges with which to draw a circle.
radius
The radius of the sectors.
col
The colors with which to fill the sectors.
align.at
Where to align the sectors (see Details).
max.span
The angle of the maximal sector in radians. The default is to scale x so that it sums to 2*pi.
labels
Labels placed around the sector arcs.
labelpos
Optional circumferential positions for the labels.
label.radius
How far away from the sectors the labels will be placed. May be a vector with a radius for each label.
align
Position of the alignment of sectors (see Details).
shrink
How much to shrink each successive sector in user units.
main
Optional title for the plot.
ticks
The number of ticks that would appear if the sectors were on a pie chart. Default is no ticks, TRUE gives the number of ticks equal to the integer sum of x, which is fairly sensible if x is a vector of integers.
include.sumx
Whether to include the sum of all x values as the largest sector.
...
Additional arguments passed to polygon.
例：
iucn.df<-data.frame(area=c("Africa","Asia","Europe","N&C America",
"S America","Oceania"),threatened=c(5994,7737,1987,4716,5097,2093))
fan.plot(iucn.df$threatened,max.span=pi,
labels=paste(iucn.df$area,iucn.df$threatened,sep="-"),
main="Threatened species by geographical area (fan.plot)",ticks=276)
image.png
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