R以png格式保存绘图,但不以pdf格式保存

我想把一个玩具情节保存在一个文件里。它适用于png,但不适用于pdf。pdf是空的。

width =  1144
height = 995

png("deleteme.png", width = width, height = height)
op=par(mar = c(0, 0, 0, 0))
plot(c(0, width), c(0, height), type = "n", xlab = "", ylab = "",xaxs = "i",yaxs = "i")
lines(c(1,2,3,4)*100, c(3,2,3,5)*100)
dev.off()

pdf("deleteme.pdf", width = width, height = height)
op=par(mar = c(0, 0, 0, 0))
plot(c(0, width), c(0, height), type = "n", xlab = "", ylab = "",xaxs = "i",yaxs = "i")
lines(c(1,2,3,4)*100, c(3,2,3,5)*100)
dev.off()

这是png:

http://docdro.id/wG9xx3J

pdf在chrome中显示行,但在Acrobat中不显示!