使用 ggplot2 绘制二部网络图

我有以下数据框：

structure(list(X1 = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 4L, 4L, 
4L, 4L, 4L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 6L, 6L, 6L
), .Label = c("1", "2", "3", "4", "5", "6"), class = "factor"), 
    X2 = structure(c(1L, 6L, 8L, 10L, 12L, 13L, 3L, 4L, 1L, 6L, 
    7L, 9L, 10L, 12L, 13L, 3L, 4L, 5L, 10L, 12L, 13L, 4L, 1L, 
    6L, 12L, 13L, 3L, 1L, 6L, 7L, 8L, 10L, 11L, 12L, 13L, 2L, 
    3L, 11L, 12L, 13L), .Label = c("I1", "I10", "I11", "I12", 
    "I13", "I2", "I3", "I4", "I5", "I6", "I7", "I8", "I9"), class = "factor")), .Names = c("X1", 
"X2"), row.names = c(NA, -40L), class = "data.frame")

其中 X1 是人员编号，X2 是人员所属的组。一个人可以属于不同的组。 现在我想从每个人到他所属的每个组画一条线。和plot()我是这样解决的：

plot(0, xlim=c(0,1), ylim=c(0,1), type="n", axes=FALSE, xlab="", ylab="")

factor.to.int <- function(f) {
  (as.integer(f) - 1) / (length(levels(f)) - 1)
}

segments(factor.to.int(data$X1), 0, factor.to.int(data$X2), 1, col=data$X1)
axis(1, at = seq(0, 1, by = 1 / (length(levels(data$X1)) - 1)), labels = levels(data$X1))
axis(3, at = seq(0, 1, by = 1 / (length(levels(data$X2)) - 1)), labels = levels(data$X2))

The result looks like this:

现在我想知道如何使用 ggplot2 做到这一点？

感谢您的帮助！

一个简单的ggplot2您的图表的版本可以通过使用geom_segment()并像对基本图形版本所做的那样转换数据。我还使用了 ggplot2 中一些更高级的自定义选项，提供了一个可以说更精致的版本。

# Using ggplot2 version 0.9.2.1
library(ggplot2)

dat$x1_norm = rangeTransform(as.integer(dat$X1))
dat$x2_norm = rangeTransform(as.integer(dat$X2))

dat$y1 = 0
dat$y2 = 1

# Simple version.
p1 = ggplot(dat, aes(x=x1_norm, xend=x2_norm, y=y1, yend=y2, colour=X1)) +
     geom_segment(size=1.2) +
     scale_colour_brewer(palette="Set1", name="Person")

ggsave(plot=p1, filename="plot_1.png", height=3.5, width=6)

# Fancy version.
# Create separate data.frames to manually specify axis ticks and axis text.
axis_1 = data.frame(x=rangeTransform(as.integer(unique(dat$X1))),
                    y=0, label=as.character(unique(dat$X1)))

axis_2 = data.frame(x=rangeTransform(as.integer(unique(dat$X2))),
                    y=1, label=as.character(unique(dat$X2)))

p2 = ggplot(data=dat) +
     theme_bw() +
     theme(axis.title=element_blank()) +
     theme(axis.text=element_blank()) +
     theme(axis.ticks=element_blank()) +
     theme(panel.grid=element_blank()) +
     geom_segment(aes(x=x1_norm, xend=x2_norm, y=y1, yend=y2, colour=X1),
                  size=1.2) +
     geom_segment(x=0, xend=1, y=0, yend=0, size=0.7) +
     geom_segment(x=0, xend=1, y=1, yend=1, size=0.7) +
     scale_colour_brewer(palette="Set1", name="Person") +
     scale_y_continuous(limits=c(-0.2, 1.2), expand=c(0, 0)) +
     geom_segment(data=axis_1, aes(x=x, xend=x, y=y, yend=y-0.025), size=0.7) +
     geom_segment(data=axis_2, aes(x=x, xend=x, y=y, yend=y+0.025), size=0.7) +
     geom_text(data=axis_1, aes(label=label, x=x, y=y - 0.075)) +
     geom_text(data=axis_2, aes(label=label, x=x, y=y + 0.075))

ggsave(plot=p2, filename="plot_2.png", height=3.5, width=6)