ggplot折线图无法正确显示数据

Question

我正在尝试尽可能具体。 我正在使用的数据如下：

      dates bsheet      mro      ciss
1  2008 Oct 490509 3.751000 0.8579982
2  2008 Nov 513787 3.434333 0.9153926
3  2008 Dec 570591 2.718742 0.9145012
4  2009 Jan 534985 2.323581 0.8811410
5  2009 Feb 528390 2.001000 0.8551557
6  2009 Mar 551730 1.662290 0.8286146
7  2009 Apr 514041 1.309333 0.7460113
8  2009 May 486151 1.097774 0.5925725
9  2009 Jun 484629 1.001000 0.5412631
10 2009 Jul 454379 1.001000 0.5398128
11 2009 Aug 458111 1.001000 0.3946989
12 2009 Sep 479956 1.001000 0.2232348
13 2009 Oct 448080 1.001000 0.2961637
14 2009 Nov 427756 1.001000 0.3871220
15 2009 Dec 448548 1.001000 0.3209175

并且可以通过

生成

structure(list(dates = c("2008 Oct", "2008 Nov", "2008 Dec", 
"2009 Jan", "2009 Feb", "2009 Mar", "2009 Apr", "2009 May", "2009 Jun", 
"2009 Jul", "2009 Aug", "2009 Sep", "2009 Oct", "2009 Nov", "2009 Dec"
), bsheet = c(490509, 513787, 570591, 534985, 528390, 551730, 
514041, 486151, 484629, 454379, 458111, 479956, 448080, 427756, 
448548), mro = c(3.751, 3.43433333333333, 2.71874193548387, 2.32358064516129, 
2.001, 1.66229032258065, 1.30933333333333, 1.09777419354839, 
1.001, 1.001, 1.001, 1.001, 1.001, 1.001, 1.001), ciss = c(0.857998173913043, 
0.9153926, 0.914501173913044, 0.881140954545454, 0.85515565, 
0.828614636363636, 0.746011318181818, 0.592572476190476, 0.541263136363636, 
0.539812782608696, 0.394698857142857, 0.223234772727273, 0.296163727272727, 
0.387122047619048, 0.32091752173913)), row.names = c(NA, 15L), class = "data.frame")

我使用以下代码创建的折线图

  ciss_plot = ggplot(data = example) + 
    geom_line(aes(x = dates, y = ciss, group = 1)) +
    labs(x = 'Time', y = 'CISS') + 
    scale_x_discrete(breaks = dates_breaks, labels = dates_labels) +
    scale_y_continuous(limits = c(0, 1), breaks = c(seq(0, 0.8, by = 0.2)), expand = c(0, 0)) +
    theme_bw() +
    theme(axis.text.x = element_text(hjust = c(rep(0.5, 11), 0.8, 0.2))) 
  ciss_plot

ggplot2的

如下：

如果使用R内置的plot（）函数中的标准绘制相同的数据，则使用

  plot(example$ciss, type = 'l')

产生

显然不一样！

有人可以帮我吗？这些情节已经把我带走了，我还没有弄清楚问题出在哪里。我怀疑是“ group = 1”或example $ dates列的数据类型在搞砸！

感谢任何建设性的投入！

谢谢大家！

Manuel

Answer 1

您的date列为字符格式。这意味着ggplot将默认将其转换为因子并按字母顺序排列，这就是为什么图形以不同的形状出现的原因。解决此问题的一种方法是在绘制之前确保水平顺序正确，如下所示：

library(dplyr)
library(ggplot2)

dates_breaks <- as.character(example$dates)

ggplot(data = example %>% mutate(dates = factor(dates, levels = dates))) + 
    geom_line(aes(x = dates, y = ciss, group = 1)) +
    labs(x = 'Time', y = 'CISS') + 
    scale_x_discrete(breaks = dates_breaks, labels = dates_breaks,
                     guide = guide_axis(n.dodge = 2)) +
    scale_y_continuous(limits = c(0, 1), breaks = c(seq(0, 0.8, by = 0.2)),
                       expand = c(0, 0)) +
    theme_bw()

一种更聪明的方法是将date列转换为实际日期时间，这样可以提高绘图的自由度，并且完全不必使用分组变量：

example <- example %>%
  mutate(dates = as.POSIXct(strptime(paste(dates, "01"), "%Y %b %d")))
  
ggplot(example) + 
  geom_line(aes(x = dates, y = ciss, group = 1)) +
  labs(x = 'Time', y = 'CISS') + 
  scale_y_continuous(limits = c(0, 1), breaks = c(seq(0, 0.8, by = 0.2)),
                     expand = c(0, 0)) +
  scale_x_datetime(breaks = seq(min(example$dates), max(example$dates), "year"),
                   labels = function(x) strftime(x, "%Y\n%b")) +
  theme_bw() +
  theme(panel.grid.minor.x = element_blank())