ggplot2 eval（expr，envir，enclos）中的错误：找不到对象

Question

数据集

> dput(head(spdistbc,50))
structure(list(Lane = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L), Vehicle.class = c(2L, 2L, 2L, 
2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), 
    speedmph = c(0, 3.4, 6.8, 10.2, 13.6, 17, 20.4, 23.8, 27.2, 
    30.6, 34, 37.4, 40.8, 0, 3.4, 6.8, 10.2, 13.6, 17, 20.4, 
    23.8, 27.2, 30.6, 34, 37.4, 40.8, 3.4, 6.8, 10.2, 13.6, 17, 
    20.4, 23.8, 27.2, 30.6, 34, 37.4, 40.8, 0, 3.4, 6.8, 10.2, 
    13.6, 17, 20.4, 23.8, 27.2, 30.6, 34, 37.4), cprob = c(0, 
    0, 0.03, 0.06, 0.11, 0.2, 0.28, 0.43, 0.56, 0.75, 0.91, 0.97, 
    1, 0, 0, 0.01, 0.01, 0.02, 0.05, 0.17, 0.36, 0.57, 0.76, 
    0.93, 0.99, 1, 0, 0.01, 0.01, 0.04, 0.07, 0.16, 0.32, 0.55, 
    0.76, 0.94, 0.99, 1, 0, 0, 0, 0.01, 0.03, 0.06, 0.11, 0.25, 
    0.47, 0.74, 0.92, 0.98)), .Names = c("Lane", "Vehicle.class", 
"speedmph", "cprob"), row.names = c(7L, 8L, 9L, 10L, 11L, 12L, 
13L, 14L, 15L, 16L, 17L, 18L, 19L, 26L, 27L, 28L, 29L, 30L, 31L, 
32L, 33L, 34L, 35L, 36L, 37L, 38L, 42L, 43L, 44L, 45L, 46L, 47L, 
48L, 49L, 50L, 51L, 52L, 53L, 66L, 67L, 68L, 69L, 70L, 71L, 72L, 
73L, 74L, 75L, 76L, 77L), class = "data.frame")

> dput(head(cspdistbv,50))
structure(list(lanem = c(6L, 6L, 6L, 6L, 6L, 6L, 6L, 7L, 7L, 
7L, 7L, 7L, 7L, 7L, 7L, 7L, 8L, 8L, 8L, 8L, 8L, 9L, 9L, 9L, 9L, 
9L, 9L, 9L, 10L, 10L, 10L, 10L, 10L, 10L, 10L, 11L, 11L, 11L, 
11L, 11L), cars = structure(c(34, 35, 36, 37, 38, 39, 40, 24, 
26, 28, 30, 32, 34, 36, 38, 40, 20, 25, 30, 35, 40, 10, 15, 20, 
25, 30, 35, 40, 10, 15, 20, 25, 30, 35, 40, 35, 40, 45, 50, 55, 
0, 0.03, 0.07, 0.17, 0.67, 0.93, 1, 0, 0.03, 0.1, 0.1, 0.2, 0.27, 
0.33, 0.8, 1, 0, 0.1, 0.31, 0.52, 1, 0, 0.07, 0.27, 0.37, 0.5, 
0.77, 1, 0, 0.03, 0.07, 0.23, 0.4, 0.77, 1, 0, 0.13, 0.47, 0.77, 
1), .Dim = c(40L, 2L), .Dimnames = list(NULL, c("speedmph", "prob"
)))), .Names = c("lanem", "cars"), row.names = c(NA, 40L), class = "data.frame")

问题

我使用spdistbc创建了情节：

cb1 <- ggplot() + geom_point(data = spdistbc, mapping = aes(x=speedmph, y = cprob, color = 'observed')) + facet_wrap(~Lane) + theme_bw() + my.theme()

这给了我这个：

但是当我使用以下代码组合第二个数据框中的另一个图时：

cb2 <- cb1 + geom_point(data = cspdistbv, mapping = aes(x = cars.speedmph, y = cars.prob, color = 'simulated-default')) + facet_wrap(~lanem)

我收到错误：

Error in eval(expr, envir, enclos) : object 'cars.speedmph' not found

问题

您可以在cspdistbv数据框中看到有一个名为cars.speedmph的列，那么为什么R无法找到它？请帮忙。

Answer 1

不知何故，您创建了无效的data.frame。您已在cspdistbv的第二列中存储了一个矩阵; dim(cspdistbv)认为它只有两列，这会干扰正确的命名等。我不确定你是如何创建它的，但你可以用

来修复它

cspdistbv  <- cbind.data.frame(lanem=cspdistbv[,1], cspdistbv[,2])

然后

cb1 <- ggplot() + geom_point(data = spdistbc, mapping = aes(x=speedmph, 
 y = cprob, color = 'observed')) + facet_wrap(~Lane) + theme_bw()
cb2 <- cb1 + geom_point(data = cspdistbv, mapping = aes(x = speedmph, 
 y = prob, color = 'simulated-default')) + facet_wrap(~lanem)

应该有效