浮动条形图，日期为 r 中的绘制值

Question

我想绘制特定对象处于“活动”状态的日期范围，如下所示：

这个例子取自Wikipedia。这是数据：

df1 <- data.frame(
  name = c("Eazy-E", "DJ Yella", "Dr. Dre",
    "Ice Cube", "Arabian Prince", "MC Ren"),
  from = as.Date(c("01/01/1986", "01/01/1986", "01/01/1986",
    "01/01/1986", "01/01/1986","02/01/1988"), "%m/%d/%Y"),
  to = as.Date(c("08/01/1991", "08/01/1991", "07/01/1991",
    "12/01/1989", "07/01/1988", "08/01/1991"),"%m/%d/%Y"))

df1
            name       from         to
1         Eazy-E 1986-01-01 1991-08-01
2       DJ Yella 1986-01-01 1991-08-01
3        Dr. Dre 1986-01-01 1991-07-01
4       Ice Cube 1986-01-01 1989-12-01
5 Arabian Prince 1986-01-01 1988-07-01
6         MC Ren 1988-02-01 1991-08-01

我不知道该怎么做：

1. 绘制日期值
2. 制作浮动条形图

感谢您的任何意见。

Answer 1

它本身似乎不是条形图，更像是线条或矩形的集合。因此，这可以通过lines()、rect() 甚至polygon() 来解决。我将展示第一个，希望你能明白要点。

您的数据：

dat <- structure(list(name = c("Eazy-E", "DJ Yella", "Dr. Dre", "Ice Cube", "Arabian Prince", "MC Ren"),
                      from = c("1986-01-01", "1986-01-01", "1986-01-01", "1986-01-01", "1986-01-01", "1988-02-01"),
                      to = c("1991-08-01", "1991-08-01", "1991-07-01", "1989-12-01", "1988-07-01", "1991-08-01")),
                 .Names = c("name", "from", "to"), row.names = c(NA, -6L), class = "data.frame")
dat$from <- as.POSIXct(dat$from)
dat$to <- as.POSIXct(dat$to)
dat
##             name       from         to
## 1         Eazy-E 1986-01-01 1991-08-01
## 2       DJ Yella 1986-01-01 1991-08-01
## 3        Dr. Dre 1986-01-01 1991-07-01
## 4       Ice Cube 1986-01-01 1989-12-01
## 5 Arabian Prince 1986-01-01 1988-07-01
## 6         MC Ren 1988-02-01 1991-08-01

一个解决方案：

par(mar=c(2,8,0,0) + 0.1)
plot(0, type='n', xlim=range(c(dat$from, dat$to)), ylim=c(1, nrow(dat)),
     main='', xlab='', ylab='', xaxt='n', yaxt='n')
years <- seq.POSIXt(min(dat$from), max(dat$to), by='1 year')
abline(v=years, lty=3, col='gray')
axis(1, at=years, labels=format(years, '%Y'))
axis(2, at=1:nrow(dat), labels=rev(dat$name), las=2)
lines(x=as.POSIXct(c(apply(dat[,c('from','to')], 1, c, NA))),
      y=rep(nrow(dat):1, each=3),
      lwd=5)

增加lwd 以获得更粗的线条。如果您想对其进行更多控制，请考虑以同样的方式使用rect。

Answer 2

这是一种使用barchart 的方法。首先，绘制一个条形图，其中条形长度由结束日期给出，然后在此上面绘制一个白色条形图，条形长度由开始日期给出。使用axis.date 添加 x 轴标签。

par(mar=c(5, 6, 2, 2))
b <- barplot(as.numeric(df$to), horiz=TRUE, border='transparent', 
        xlim=range(c(df$from, df$to)), xaxt='n', yaxs='i',
        space=1)
barplot(as.numeric(df$from), horiz=TRUE, space=1, add=TRUE, col='white', 
        border='transparent', xaxt='n', names.arg=df$name, las=1, 
        cex.names=0.8)
axis(2, at=b[, 1], labels=FALSE, tick=FALSE)
box(bty='l')
axis.Date(1, pretty(df$from), cex.axis=0.8)