在图（R）中围绕圆圈包裹/弯曲文本

Question

是否有机会撰写被包裹的文字＆＃34;绕圈？我的意思是这样的：

Answer 1

是的，这是代码，免费:-)。我曾经写过一段时间，但我认为我不会在任何CRAN包中发布它。

# Plot symbols oriented to local slope.
# Interesting problem: if underlying plot has some arbitrary aspect ratio,
# retrieve by doing: Josh O'B via SO:  
# myasp <- with(par(),(pin[2]/pin[1])/(diff(usr[3:4])/diff(usr[1:2])))
# so make that the default value of argument 'asp'
# Default is 'plotx' is vector of indices at which to 
# plot symbols.  If is_indices=FALSE, only then turn to splinefun to 
# calculate y-values and slopes; and user beware.
#
# 6 Feb 2014: added default col arg so can stick in a color vector if desired
# TODO
#
slopetext<-function(x,y,plotx, mytext, is_indices=TRUE, asp=with(par(), (pin[1]/pin[2])*(diff(usr[3:4])/diff(usr[1:2]))),offsetit= 0, col='black', ...) {
if (length(x) != length(y)) stop('data length mismatch')
if (!is.numeric(c(x,y,plotx) ) ) stop('data not numeric')
if(is_indices) {
    # plotting at existing points.
    if(any(plotx<=1) | any(plotx>= length(x))) {
        warning("can't plot endpoint; will remove")
        plotx<-plotx[(plotx>1 & plotx<length(x))]
    }
    lows<-plotx-1
    highs<-plotx+1
    # then interpolate low[j],high[j] to get slope at x2[j]
    slopes <- (y[highs]-y[lows])/(x[highs]-x[lows])  #local slopes
    # sign(highlow)  fix the rotation problem 
    angles <- 180/pi*atan(slopes/asp)  + 180*(x[lows] > x[highs] )
    intcpts <- y[highs]-slopes*x[highs]   
    ploty <- intcpts + x[plotx]*slopes
    # change name, so to speak, to simplify common plotting code
    plotx<-x[plotx]
    }else{
    #interpolating at plotx values
        if  (any(plotx<min(x)) | any(plotx>max(x)) ) {
            warning("can't plot extrapolated point; will remove")
            plotx<-plotx[(plotx>min(x) & plotx<max(x))]
        }
        spf<-splinefun(x,y)
        ploty<-spf(plotx)
        angles <- 180/pi * atan(spf(plotx,1)/asp) #getting first deriv, i.e. slope
    } #end of else
xlen<-length(plotx) # better match y and mytext
# The trouble is: srt rotates about some non-centered value in the text cell
# Dunno what to do about that.
dely <- offsetit*cos(angles)
delx <- offsetit*sin(angles)
# srt must be scalar
mytext<-rep(mytext,length=xlen)
col <- rep(col,length=xlen)
for (j in 1:xlen) text(plotx[j], ploty[j], labels=mytext[j], srt= angles[j], adj=c(delx,dely),col=col[j], ...)
}

编辑：根据大卫的优秀建议，示例：

x <- 1:100
y <- x/20 + sin(x/10)
plot(x,y,t='l')
slopetext(x=x,y=y,plotx=seq(10,70,by=10),mytext=letters[1:8])

此示例中的第三个参数选择（x，y）的每个第十个值来放置文本。 我应该警告说，我is_indices=FALSE案件并没有发出傻瓜的证据，而且在极端情况下，样条可能会以有趣的方式放置文本。

Answer 2

您也可以在arctext包中尝试plotrix：

library(plotrix)

# set up a plot with a circle
plot(x = 0, y = 0, xlim = c(-2, 2), ylim = c(-2, 2))
draw.circle(x = 0, y = 0, radius = 1)

# add text
arctext(x = "wrap some text", center = c(0, 0), radius = 1.1, middle = pi/2)
arctext(x = "counterclockwise", center = c(0, 0), radius = 1.1, middle = 5*pi/4,
        clockwise = FALSE, cex = 1.5)
arctext(x = "smaller & stretched", center = c(0, 0), radius = 1.1, middle = 2*pi ,
        cex = 0.8, stretch = 1.2)

为了获得更多的定制机会（轻描淡写;请参阅精彩的小插曲），您可以查看circlize包。通过在facing = "bending"中设置circos.text，文字会围绕一个圆圈。

library(circlize)

# create some angles, labels and their corresponding factors
# which determine the sectors 
deg <- seq(from = 0, to = 300, by = 60)
lab <- paste("some text", deg, "-", deg + 60)   
factors <- factor(lab, levels = lab)

# initialize plot
circos.par(gap.degree = 10)
circos.initialize(factors = factors, xlim = c(0, 1))
circos.trackPlotRegion(ylim = c(0, 1))

# add text to each sector  
lapply(factors, function(deg){
  circos.updatePlotRegion(sector.index = deg, bg.col = "red")
circos.text(x = 0.5, y = 0.5, labels = as.character(deg), facing = "bending")
})
circos.clear()

<强>更新：
在circlize version 0.2.1中，circos.text有两个新选项：bending.inside与原始bending和bending.outside相同（参见the vignette中的图11）。因此，使用bending.outside：

可以轻松地在图的下半部分中翻译文本

circos.par(gap.degree = 10)
circos.initialize(factors = factors, xlim = c(0, 1))
circos.trackPlotRegion(ylim = c(0, 1))

lapply(factors[1:3], function(deg){
  circos.updatePlotRegion(sector.index = deg, bg.col = "red")
  circos.text(x = 0.5, y = 0.5, labels = as.character(deg), facing = "bending.outside")
})

lapply(factors[4:6], function(deg){
  circos.updatePlotRegion(sector.index = deg, bg.col = "red")
  circos.text(x = 0.5, y = 0.5, labels = as.character(deg), facing = "bending.inside")
})
circos.clear()