ggplot2仅限营业时间之间的时间序列

Question

我目前有一个ggplot2图表，如下所示：

数据框如下所示：

           city weekday     time avg_wait_time           timestamp
1511 Boston Tuesday 09:06 AM          0.20 2001-01-04 09:06:00
1512 Boston Tuesday 09:07 AM          0.20 2001-01-04 09:07:00
1513 Boston Tuesday 09:08 AM          0.20 2001-01-04 09:08:00
1514 Boston Tuesday 09:09 AM          3.17 2001-01-04 09:09:00
1515 Boston Tuesday 09:10 AM          3.17 2001-01-04 09:10:00
1516 Boston Tuesday 09:11 AM          3.17 2001-01-04 09:11:00
1517 Boston Tuesday 09:12 AM          3.17 2001-01-04 09:12:00
1518 Boston Tuesday 09:13 AM          5.87 2001-01-04 09:13:00
1519 Boston Tuesday 09:14 AM          5.87 2001-01-04 09:14:00
1520 Boston Tuesday 09:15 AM          5.87 2001-01-04 09:15:00
1521 Boston Tuesday 09:16 AM          5.87 2001-01-04 09:16:00
1522 Boston Tuesday 09:17 AM          9.17 2001-01-04 09:17:00
1523 Boston Tuesday 09:18 AM          9.17 2001-01-04 09:18:00
1524 Boston Tuesday 09:19 AM         12.20 2001-01-04 09:19:00
1525 Boston Tuesday 09:20 AM         12.20 2001-01-04 09:20:00
1526 Boston Tuesday 09:21 AM         12.10 2001-01-04 09:21:00
1527 Boston Tuesday 09:23 AM         13.70 2001-01-04 09:23:00
1528 Boston Tuesday 09:24 AM         13.70 2001-01-04 09:24:00
1529 Boston Tuesday 09:25 AM         15.30 2001-01-04 09:25:00
1530 Boston Tuesday 09:26 AM         15.30 2001-01-04 09:26:00
1531 Boston Tuesday 09:27 AM         16.90 2001-01-04 09:27:00
1532 Boston Tuesday 09:28 AM         16.90 2001-01-04 09:28:00
1533 Boston Tuesday 09:29 AM         18.33 2001-01-04 09:29:00
1534 Boston Tuesday 09:30 AM         18.33 2001-01-04 09:30:00
1535 Boston Tuesday 09:31 AM         16.90 2001-01-04 09:31:00
1536 Boston Tuesday 09:32 AM         16.90 2001-01-04 09:32:00
1537 Boston Tuesday 09:33 AM         18.57 2001-01-04 09:33:00
1538 Boston Tuesday 09:34 AM         18.57 2001-01-04 09:34:00
1539 Boston Tuesday 09:35 AM         21.73 2001-01-04 09:35:00
1540 Boston Tuesday 09:36 AM         21.73 2001-01-04 09:36:00

此数据框的类是：

> sapply(x_output, class)
$city
[1] "factor"

$weekday
[1] "factor"

$time
[1] "character"

$avg_wait_time
[1] "numeric"

$timestamp
[1] "POSIXct" "POSIXt" 

从图中可以看出，由于ggplot2正在绘制一个24小时的日期，因此空格太多了。在此数据集中，数据是一个工作周的时间段(2001-01-01 to 2001-01-05)（“平均”周，任意设置这些特定日期），营业时间介于9am and 6pm之间。

如何在上午9点到下午6点之间制作ggplot2图？

这是我的尝试：

p <- ggplot(x_output, aes(x=timestamp, y=avg_wait_time, group=city)) +
  geom_line(aes(color=city), size=1.5) + 
  theme(axis.text.x = element_text(angle = 90, hjust=1), 
        legend.position = "bottom") + 
  labs(x=NULL, y="Waiting time (minutes)") + 
  facet_wrap( ~ weekday, ncol=5) + 
  scale_x_datetime(breaks = date_breaks("1 hour")), 
                   limits = c(as.POSIXct("9:00"), as.POSIXct("18:00"))

print(p)

我认为如果我能正确配置limits部分，ggplot2将正确绘制。谢谢你的帮助。

更新：我只是靠近了一点（参见scales部分）：

p <- ggplot(x_output, aes(x=timestamp, y=avg_wait_time, group=city)) +
  geom_line(aes(color=city), size=1.5) + 
  theme(axis.text.x = element_text(angle = 90, hjust=1),
        legend.position = "bottom") + 
  labs(x=NULL, y="Waiting time (minutes)") + 
  facet_wrap( ~ weekday, ncol=5, **scales="free"**) +
  scale_x_datetime(breaks = date_breaks("1 hour"), 
                   labels=date_format("%H:%M"))

现在我的输出如下：

但是，从图像中可以看出，轴是错误的，并且不反映数据。数据看起来像（我也在这里复制：http://pastebin.com/sDhzkHPC）：

> r <- r[order(r$timestamp),]
> head(r,15)
       city  weekday     time avg_wait_time           timestamp
2714 Boston Thursday 10:04 AM          0.00 2001-01-06 10:04:00
2715 Boston Thursday 10:05 AM          0.00 2001-01-06 10:05:00
2716 Boston Thursday 10:06 AM          0.23 2001-01-06 10:06:00
2717 Boston Thursday 10:07 AM          0.23 2001-01-06 10:07:00
2718 Boston Thursday 10:08 AM          3.33 2001-01-06 10:08:00
2719 Boston Thursday 10:09 AM          3.33 2001-01-06 10:09:00
2720 Boston Thursday 10:10 AM          4.80 2001-01-06 10:10:00
2721 Boston Thursday 10:11 AM          4.80 2001-01-06 10:11:00
2722 Boston Thursday 10:12 AM          6.33 2001-01-06 10:12:00
2723 Boston Thursday 10:13 AM          6.33 2001-01-06 10:13:00
2724 Boston Thursday 10:14 AM          7.90 2001-01-06 10:14:00
2725 Boston Thursday 10:15 AM          7.90 2001-01-06 10:15:00
2726 Boston Thursday 10:16 AM          9.50 2001-01-06 10:16:00
2727 Boston Thursday 10:17 AM          9.50 2001-01-06 10:17:00
2728 Boston Thursday 10:18 AM         12.17 2001-01-06 10:18:00
> tail(r,15)
       city  weekday     time avg_wait_time           timestamp
2699 Boston Thursday 05:41 PM         22.07 2001-01-06 17:41:00
2700 Boston Thursday 05:42 PM         23.47 2001-01-06 17:42:00
2701 Boston Thursday 05:43 PM         23.47 2001-01-06 17:43:00
2702 Boston Thursday 05:44 PM         24.90 2001-01-06 17:44:00
2703 Boston Thursday 05:45 PM         24.90 2001-01-06 17:45:00
2704 Boston Thursday 05:46 PM         26.43 2001-01-06 17:46:00
2705 Boston Thursday 05:47 PM         19.33 2001-01-06 17:47:00
2706 Boston Thursday 05:49 PM         12.23 2001-01-06 17:49:00
2707 Boston Thursday 05:50 PM          0.00 2001-01-06 17:50:00
2708 Boston Thursday 05:52 PM          0.23 2001-01-06 17:52:00
2709 Boston Thursday 05:54 PM          1.80 2001-01-06 17:54:00
2710 Boston Thursday 05:55 PM          1.80 2001-01-06 17:55:00
2711 Boston Thursday 05:56 PM          0.00 2001-01-06 17:56:00
2712 Boston Thursday 05:57 PM          0.00 2001-01-06 17:57:00
2713 Boston Thursday 05:58 PM          0.00 2001-01-06 17:58:00

更新2：这是一个时区问题。

我使用此资源解决了它：plotting times with ggplot: added hour in plot maybe due to daylight saving?

更具体地说，我做了：

tz(x_output$timestamp) <- "GMT" # "America/New_York"

该评论仅用于试验测试几个不同的时区，以查看哪些匹配（可在此处找到：http://www.inside-r.org/packages/cran/lubridate/docs/tz）。

我会为后人保留这个问题。

Answer 1

我的方法不是使用x轴的时间戳，而是使用时间。

x_output$time <- strftime(timestamp, format="%H:%M")

然后使用具有相同工作日方面的此调用设置ggplot应该有效。

p <- ggplot(x_output, aes(x=time, y=avg_wait_time, group=city))

注意：目前无法访问R环境，因此我无法直接验证此代码是否有效，但原则上应该：:)