设置日期时间 X 轴、ggplot 的小中断

Question

我使用以下代码将日期时间列绘制为每天的直方图。

即使将 X 轴休息时间设置为 1 天后，我得到的默认选项可能是 1 个月。如何用“年-月-日”绘制每一天的X轴？

另外，如果可能的话，我想在每个条形的顶部显示计数。

代码

data <- read.table("input.csv", sep=",", head=T)

data$datetime <- as.Date(data$datetime)

ggplot(data, aes(x=datetime)) +
  geom_histogram(binwidth=0.5, colour="black", fill="white")  + 
  scale_x_date(date_minor_breaks = "1 day")

数据

index,datetime,values,type
55,2019-11-02 12:00:00,2.2571265131358302,x
56,2019-11-02 13:00:00,2.4175854658358227,x
57,2019-11-02 14:00:00,2.7247976096720685,x
58,2019-11-02 15:00:00,3.0477882795726146,x
59,2019-11-02 16:00:00,3.2006008421516996,x
60,2019-11-02 17:00:00,3.2116870146833625,x
61,2019-11-02 18:00:00,3.4693910132468457,x
62,2019-11-02 19:00:00,3.911869748466746,x
63,2019-11-02 20:00:00,4.00069618775975,x
64,2019-11-02 22:00:00,4.0834105399449285,x
65,2019-11-02 23:00:00,4.160321416499418,x
66,2019-11-03 00:00:00,4.098125637510356,x
67,2019-11-03 01:00:00,4.021221769171646,x
68,2019-11-03 02:00:00,4.017759023510684,x
69,2019-11-03 03:00:00,4.013082714411543,x
70,2019-11-03 04:00:00,4.057993925343051,x
71,2019-11-03 05:00:00,4.194095193140784,x
72,2019-11-03 07:00:00,4.294259567020734,x
73,2019-11-03 08:00:00,4.337746909001244,x
74,2019-11-03 09:00:00,4.384365666444803,x
75,2019-11-03 10:00:00,4.448100962130655,x
76,2019-11-03 11:00:00,4.501990074404225,x
77,2019-11-03 13:00:00,4.52830137381731,x
78,2019-11-03 14:00:00,4.647279146289785,x
79,2019-11-03 15:00:00,4.776722797787091,x
80,2019-11-03 19:00:00,4.696071186160853,x
81,2019-11-03 21:00:00,4.57669998620599,x
82,2019-11-03 22:00:00,4.462372935827071,x
83,2019-11-03 23:00:00,4.29887239487861,x
84,2019-11-04 00:00:00,4.138775537444896,x
85,2019-11-04 01:00:00,4.010458288624996,x
86,2019-11-04 02:00:00,3.8001917855220837,x
87,2019-11-04 03:00:00,3.5833796414675563,x
88,2019-11-04 04:00:00,3.4035716671606404,x
89,2019-11-04 05:00:00,3.272242285475774,x
90,2019-11-04 06:00:00,3.103512688095525,x
91,2019-11-04 08:00:00,3.1125352688100882,x
92,2019-11-04 09:00:00,3.220763083848201,x
93,2019-11-04 10:00:00,3.290134157323074,x
94,2019-11-04 11:00:00,3.415488671370309,x
95,2019-11-04 12:00:00,3.5455879768850576,x
96,2019-11-04 13:00:00,3.5474491297923727,x
97,2019-11-04 14:00:00,3.783816611089137,x
98,2019-11-04 15:00:00,4.184648621004391,x
99,2019-11-04 16:00:00,4.2413488810807864,x
100,2019-11-04 18:00:00,4.179690857096466,x
101,2019-11-05 08:00:00,4.186025943693791,x
102,2019-11-05 09:00:00,4.028004946673923,x
103,2019-11-05 12:00:00,3.996324873094708,x
104,2019-11-05 14:00:00,4.170572049548053,x
105,2019-11-05 15:00:00,4.324133816110184,x
106,2019-11-05 16:00:00,4.38233647529367,x
107,2019-11-05 17:00:00,4.375290157364679,x
108,2019-11-05 18:00:00,4.360382781128352,x
109,2019-11-05 19:00:00,4.264913977361403,x
110,2019-11-05 20:00:00,4.1399117448002025,x
111,2019-11-05 21:00:00,4.181169914887134,x
112,2019-11-05 22:00:00,4.251114951814682,x
113,2019-11-06 00:00:00,4.235355868286902,x
114,2019-11-06 01:00:00,4.246615325280132,x
115,2019-11-06 02:00:00,4.2108788354127595,x
116,2019-11-06 03:00:00,4.150994459861172,x
117,2019-11-06 04:00:00,4.053771508278776,x
118,2019-11-06 05:00:00,3.9656677100404196,x
119,2019-11-06 06:00:00,3.891497364440651,x
120,2019-11-06 07:00:00,3.9250961484429268,x
121,2019-11-06 09:00:00,3.9564409947149786,x
122,2019-11-06 10:00:00,3.934135576221536,x
123,2019-11-06 11:00:00,3.811665254552286,x
124,2019-11-06 13:00:00,3.698395441791204,x
125,2019-11-06 14:00:00,3.6541064673462826,x
126,2019-11-06 15:00:00,3.594042699299084,x
127,2019-11-06 16:00:00,3.450994105235735,x
128,2019-11-06 17:00:00,3.3646913567819343,x
129,2019-11-06 18:00:00,3.2999220715176176,x
130,2019-11-06 19:00:00,3.258550773145985,x
131,2019-11-06 21:00:00,3.2225326106631136,x
132,2019-11-06 22:00:00,3.185935446208913,x
133,2019-11-06 23:00:00,3.1472600656989873,x
134,2019-11-07 00:00:00,3.096357252528618,x
135,2019-11-07 01:00:00,3.0201448403174727,x
136,2019-11-07 02:00:00,3.019167468392874,x
137,2019-11-07 03:00:00,3.065834385577178,x
138,2019-11-07 05:00:00,3.111118977817557,x
139,2019-11-07 06:00:00,2.997443808096788,x
140,2019-11-07 07:00:00,2.9863646062096496,x
141,2019-11-07 08:00:00,2.9854114565645036,x
142,2019-11-07 09:00:00,2.976881175704244,x
143,2019-11-07 10:00:00,2.9485472925204563,x
144,2019-11-07 11:00:00,2.9052588427934265,x
145,2019-11-07 12:00:00,2.8723489707552354,x
146,2019-11-07 13:00:00,2.787288523493735,x
147,2019-11-07 14:00:00,2.699838153360574,x
148,2019-11-07 15:00:00,2.7790335378861903,x
149,2019-11-07 16:00:00,2.7701168032009678,x
150,2019-11-07 17:00:00,2.7599015900121775,x
151,2019-11-07 18:00:00,2.734276786826625,x
152,2019-11-07 19:00:00,2.6166425495004892,x
153,2019-11-07 20:00:00,2.480661023265874,x
154,2019-11-08 01:00:00,2.3245284179813024,x
155,2019-11-08 02:00:00,2.1160992644464174,x
156,2019-11-08 03:00:00,2.0041605300101835,x
157,2019-11-08 04:00:00,1.8515859873500127,x
598,2019-12-29 22:00:00,1.6110582697766904,x
599,2019-12-29 23:00:00,1.6596777339084172,x
600,2019-12-30 00:00:00,1.6872956896946691,x
601,2019-12-30 01:00:00,1.681427364032406,x
602,2019-12-30 02:00:00,1.6646005456192854,x
603,2019-12-30 03:00:00,1.61024577041883,x
787,2020-01-12 20:00:00,1.432215548619208,x
788,2020-01-12 21:00:00,1.482798113602255,x
789,2020-01-12 22:00:00,1.5180138321075316,x
790,2020-01-12 23:00:00,1.5862635616643168,x
791,2020-01-13 00:00:00,1.624179322341154,x
792,2020-01-13 01:00:00,1.5897191079933364,x
793,2020-01-13 02:00:00,1.5686478770443524,x
794,2020-01-13 03:00:00,1.5158600949449366,x
795,2020-01-13 04:00:00,1.4760764670728665,x
796,2020-01-13 05:00:00,1.4869610695066484,x
797,2020-01-13 07:00:00,1.5493409766366932,x
798,2020-01-13 08:00:00,1.6101944516836666,x
799,2020-01-13 09:00:00,1.6237659716487467,x
800,2020-01-13 10:00:00,1.6041134677825444,x
801,2020-01-13 11:00:00,1.5903269214934665,x
802,2020-01-13 13:00:00,1.536524696499736,x
803,2020-01-13 14:00:00,1.494193483950321,x
804,2020-01-13 15:00:00,1.4816960437129962,x
805,2020-01-13 16:00:00,1.5132917235386587,x
806,2020-01-13 18:00:00,1.6435825530166581,x
807,2020-01-13 19:00:00,1.8375058361044376,x
808,2020-01-13 20:00:00,1.9585768838462818,x
809,2020-01-13 21:00:00,1.9788951029564366,x
810,2020-01-13 22:00:00,1.9860829813291714,x
811,2020-01-13 23:00:00,1.9216810837736404,x
812,2020-01-14 00:00:00,1.86184574914949,x

Answer 1

您的原始代码按预期工作，也就是说，将 x 轴中的小中断scale_x_date(date_minor_breaks = '1 day')设置为按天分隔。次要中断未标记，而主要中断已标记。因此，您有一个按月（主要中断）分隔的轴，然后您有每天的所有短轴刻度线。

如果要按天进行标签，需要date_breaks="1 day"在 内设置scale_x_date()，然后通过指定 来指定标签的格式为YYYY-MM-DD date_labels=。

如果我们对你的代码执行此操作，你会得到以下令人讨厌的混乱：

ggplot(data, aes(x=datetime)) +
  geom_histogram(binwidth=0.5, colour="black", fill="white")  +
  scale_x_date(date_breaks = "1 day", date_labels = '%Y-%m-%d')

如果你想每天都贴上标签，你需要让这些标签合适。在这种情况下，您可以通过设置要旋转的轴文本的主题格式来实现此目的。 vjust=0.5如果您这样做，这是必要的，因为默认情况下不会将文本垂直居中对齐。

对于在每个直方图条形上方添加计数，这已在此处得到解答。不过，您的情况有点不同，因为您有很多读为“0”的值。最好只显示计数 > 0 的标签。为此，我只是在调用中构建aes(label=一个ifelse()函数，以便在标签等于 0 时将标签表示为空白。这并不意味着标签不存在...它只是意味着它包含“NA”。

您还会注意到 的y美学stat_bin设置为..count..+1。这可确保每个值都绘制在每个条形的正上方，而不是绘制在条形的边缘。你也可以乱搞，vjust让它正常工作。

ggplot(data, aes(x=datetime)) +
  geom_histogram(binwidth=0.5, colour="black", fill="white")  +
  stat_bin(aes(y=..count..+1,
    label=ifelse(..count..!=0, ..count.., NA)), geom='text', binwidth = 0.5) +
  scale_x_date(date_breaks = "1 day", date_labels = '%Y-%m-%d') +
  theme(axis.text.x = element_text(angle=90, size=7, vjust=0.5))

我个人觉得剧情可以好看一点，每天带着标签我觉得还是很难看。所以这是我的建议，让它变得时尚一点。在下面的代码中，我切换到theme_bw()（首选项），然后将主轴刻度设置为每周，次要刻度每 1 天一次。我还喜欢使用条形图（如直方图）来使条形图的底部与 x 轴相交，因此使用scale_y_continuous(expand=) 来做到这一点。最后，我格式化了轴标签以包含换行符并删除了旋转。date_breaks=不确定它是否符合您的偏好，但它也向您展示了在组合和date_minor_breaks=在同一图中可以做的更多事情。

ggplot(data, aes(x=datetime)) + theme_bw() +
  geom_histogram(binwidth=0.5, colour="black", fill="white")  +
  stat_bin(aes(y=..count..+1,
    label=ifelse(..count..!=0, ..count.., NA)), geom='text', binwidth = 0.5) +
  scale_x_date(date_breaks = "1 week", date_minor_breaks = '1 day', date_labels = '%Y\n%m-%d') +
  scale_y_continuous(expand=expansion(mult=c(0,0.05)))