Rotated x labels in R

Question

I have a data in R like the following:

   bag_id location_type            event_ts
1     155      transfer 2012-01-02 15:57:54
2     155        sorter 2012-01-02 17:06:05
3     305       arrival 2012-01-01 07:20:16
4     692       arrival 2012-03-29 09:47:52
10    748      transfer 2012-01-08 17:26:02
11    748        sorter 2012-01-08 17:30:02
12    993       arrival 2012-01-23 08:58:54
13   1019       arrival 2012-01-09 07:17:02
14   1019        sorter 2012-01-09 07:33:15
15   1154      transfer 2012-01-12 21:07:50

where class(event_ts) is "POSIXct".

I wanted to find the density of bags at each location in different times. So, I used the function density like the following:

    adj<-.00001
    dSorter<-density(as.numeric(Data$event_ts[which(Data$location_type=="sorter")]),n=length(Data$event_ts[which(Data$location_type=="sorter")]),adjust = adj) 
    StartTime<-as.POSIXct(strptime("2012-06-01", "%Y-%m-%d"), tz="UTC") # want to zoom & see part of data
    EndTime<-as.POSIXct(strptime("2012-06-3", "%Y-%m-%d"), tz="UTC")
    Range<-range(as.numeric(c(StartTime,EndTime)))
    lablist.x<-substr(seq(StartTime,EndTime,by="hour"),start=6, stop=13) # want to have time labels for my plot
    plot(dSorter, main="Sorter",xlim=Range, xaxt = "n")
    axis(1, at=as.numeric(seq(StartTime,EndTime,by="hour")), labels =F)
text(1:49,par("usr")[3] - 0.25, labels=lablist.x,srt = 45,adj=1, , xpd = TRUE) #want to rotate the labels

The last comment does not work and I do not know how should I recognize the "x" values at function "text".

Thank you in advance for any kind of comments and guidance.

Best, Shima.

Answer 1

The problem was solved, I found the coordinates that I have to use in function "text" with the command: par("usr") and changed the last line of my code as the following:

text(c(as.numeric(seq(StartTime,EndTime,by="hour"))),par("usr")[3]-(par("usr")[4]-par("usr")[3])/20,  labels=lablist.x,srt = 45,adj=1,  xpd = TRUE)