在R中的ggplot中以正确格式将点标记为日期

Question

我正在使用 R 中的 ggplot2 绘制折线图。我想以正确的日期格式命名高于某个阈值的点。

我绘制图表的代码是：

ggplot(DateSubset1, aes(TimeStamp)) + 
    geom_line(aes(y = CPU, colour = "Orange")) + 
    geom_line(aes(y = MEM), colour = "Black")+
    scale_x_datetime(date_break = "1 days")+
    geom_point(aes (x= TimeStamp, y=CPU), size = 1,colour = "Purple", 
        subset(DateSubset1, CPU>25 ))+
    geom_point(aes (x= TimeStamp, y=MEM), size = 1,colour = "Blue", 
        subset(DateSubset1, MEM>10 ))+
    scale_y_continuous(breaks = c(5,10,15,20,25,30,35,40,45,50,55,60,65,70,75,80))

我的图表如下所示：

我想用我的数据集所具有的正确日期格式标记这些点（高于某个阈值）。 我试过了

geom_text(aes(y=CPU, label= ifelse(CPU>25, TimeStamp, '')))

使用这个我的图表看起来像：

和

geom_text(aes(y= CPU,label= ifelse(CPU>25, format(TimeStamp), format = 
"%y%m%d %h%m%s",'')))

和

geom_text(aes(y= CPU, label=ifelse(CPU>25, as.Date(TimeStamp), '')))

和

geom_text(aes(y= CPU, label=ifelse(CPU>25, as.Date.POSIXct(TimeStamp), '')))

数据集字符串：

data.frame':    
1420 obs. of  3 variables:
$ TimeStamp: POSIXct, format: "2017-06-28 07:03:02" "2017-06-28 07:06:01" 
"2017-06-28 07:09:01" ...
$ CPU      : num  0.9 0.8 12.2 3.7 2.3 1.7 1.4 1.1 1 0.9 ...
$ MEM      : num  1.7 1.8 1.5 1.8 1.8 1.8 1.9 1.9 1.9 2.1 ...

示例数据如下所示：

TimeStamp                CPU   MEM
2017-06-28 07:03:02      0.9   1.7
2017-06-28 07:06:01      0.8   1.8
2017-06-28 07:09:01      12.2  1.5
2017-06-28 07:12:01      3.7   1.8
2017-06-28 07:15:01      2.3   1.8

Answer 1

好的，试试这个代码：

zz = '
   CPU   MEM
   0.9   1.7
   0.8   1.8
   12.2  1.5
'

df <- read.table(text = zz, header = TRUE)
df

TmS = c("2017-06-28 07:03:02", "2017-06-28 07:06:01", "2017-06-28 07:09:01")
df = cbind(TmS, df)
df$TmS = as.character(df$TmS)

label = as.character(ifelse(df$CPU>10, df$TmS, ''))
df$TmS = as.POSIXct(df$TmS)


ggplot(df, aes(TmS)) + 
  geom_line(aes(y = CPU, colour = "Orange")) + 
  geom_line(aes(y = MEM), colour = "Black")+
  scale_x_datetime(date_break = "1 days")+
  geom_point(aes (x= TmS, y=CPU), size = 1,colour = "Purple", 
             subset(df, CPU>10))+
  geom_point(aes (x= TmS, y=MEM), size = 1,colour = "Blue", 
             subset(df, MEM>1.5))+
  scale_y_continuous(breaks = c(5,10,15,20,25,30,35,40,45,50,55,60,65,70,75,80))+
  geom_text(aes(y= CPU, label=label))