Format date-time axis in real time histogram in R?

Question

I am trying to fix unformated date-time axis in a real time histogram. I am using like example an adaptation from Time/Date real time plot in R.

n <- 5000
df <- data.frame(time = Sys.time()+1:n, y = runif(n))
window <- 1000

for(i in 1:(n-window)) {
    flush.console()
    df1 <- df[i:(i+window), ]
    h <- hist(as.POSIXct(df1$time), breaks = "mins",  yaxt = "n", 
              col = "gray", main = NULL, freq = TRUE, xlab = "", 
              plot = FALSE, format = "%d %H:%M")
    plot(h, breaks = "mins", col = "gray", main = NULL, freq = TRUE, 
         xlab= "", format = "%d %H:%M")
    Sys.sleep(0.01)
}

Also, I did tried with half success with the code below. But lamentably the x axis show date-time like a flash and datetime axis disappear if I decrease more Sys.sleep, axis don't look so good like unformated date-time axis in my first example.

n <- 5000
df <- data.frame(time = Sys.time()+1:n, y = runif(n))
window <- 1000

for(i in 1:(n-window)) {
    flush.console()
    df1 <- df[i:(i+window), ]
    x_at <- pretty(df1$time)
    x_labels <- format(pretty(df1$time), "%d %H:%M")
    hist(df1$time, df1$y,type='l', breaks = "mins", xaxt = 'n')
    axis.POSIXct(side = 1, at = x_at, labels = x_labels)
    Sys.sleep(0.01)
}

Could be another method to see the x axis in a better way?

Answer 1

The problem is that hist() knows about time axes when you pass it a POSIXt object, but plot() doesn't when you pass it a histogram object like h. So just do everything in one step, not two:

 n=5000
 df=data.frame(time=Sys.time()+1:n,y=runif(n))
 window=1000
 for(i in 1:(n-window))
 {
    flush.console()
    df1 <-df[i:(i+window),]
    hist(as.POSIXct(df1$time), breaks="mins",  
      yaxt = "n", col="gray", main=NULL, freq = TRUE, xlab= "", 
      format = "%d %H:%M")
    Sys.sleep(0.01)
 }