It sounds to me like you want to take your data and extract one column for JUST the date and another column for just some measure of the time, such as the number of seconds since midnight or hours in a decimal format where 12:45 PM might be 12.75.
You now can graph date along the X axis and time along the Y (or vice versa) and show the result in one of many ways as points or horizontal line segments or whatever works for you. If you always had 4 time measures for each day, or did some work, you might also have a column for which time that is for a day, a number ranging from one to 4 and this column could be used to set the color or other attribute if that was useful. So, to review. Your one data item need not be kept as the only column and if you make more columns, you might have something to graph. Here is an example that worked for me doing roughly what I mentioned but note my names changed. It makes two plots. library (ggplot2) myDat <- read.table(text = "datetimeraw 2021-03-12 05:16:46 2021-03-12 09:17:02 2021-03-12 13:31:43 2021-03-12 22:00:32 2021-03-13 09:21:43 2021-03-13 13:51:12 2021-03-13 18:03:13 2021-03-13 22:20:28 2021-03-14 08:59:03 2021-03-14 13:15:56 2021-03-14 17:25:23 2021-03-14 21:36:26", sep = ",", header = TRUE) head(myDat) myDat$datetime <- as.POSIXct(myDat$datetimeraw, tz = "", format ="%Y-%M-%d %H:%M:%OS") myDat$date <- factor(format(myDat$datetime, "%Y-%m-%d")) myDat$time <- format(myDat$datetime, "%H:%M") myDat$seq <- factor(rep(1:4, 3)) # just dots ggplot(data=myDat,aes(x=date, y=time)) + geom_point(aes(color=seq)) # Also text ggplot(data=myDat,aes(x=date, y=time, label=time)) + geom_point(aes(color=seq)) + geom_text(aes(color=seq)) -----Original Message----- From: R-help <r-help-boun...@r-project.org> On Behalf Of Gregory Coats via R-help Sent: Tuesday, March 16, 2021 6:32 PM To: John Fox <j...@mcmaster.ca> Cc: r-help mailing list <r-help@r-project.org> Subject: Re: [R] How to plot dates Thank you. Let me redefine the situation. Each time an event starts, I record the date and time. Each day there are 4 new events. Time is the only variable. I would like to graphically show how the time for events 1, 2, 3, and 4 for the current day compare to the times for events 1, 2, 3, and 4 for the previous day. How would I plot / display those times differences? Greg Coats library (ggplot2) myDat <- read.table(text = "datetime 2021-03-12 05:16:46 2021-03-12 09:17:02 2021-03-12 13:31:43 2021-03-12 22:00:32 2021-03-13 09:21:43 2021-03-13 13:51:12 2021-03-13 18:03:13 2021-03-13 22:20:28 2021-03-14 08:59:03 2021-03-14 13:15:56 2021-03-14 17:25:23 2021-03-14 21:36:26", sep = ",", header = TRUE) head(myDat) myDat$datetime <- as.POSIXct(myDat$datetime, tz = "", format ="%Y-%M-%d %H:%M:%OS") > On Mar 16, 2021, at 3:34 PM, John Fox <j...@mcmaster.ca> wrote: > > Dear Greg, > > Coordinate plots typically have a horizontal (x) and vertical (y) > axis. The command > > ggplot(myDat, aes(x=datetime, y = datetime)) + geom_point() > > works, but I doubt that it produces what you want. > > You have only one variable in your data set -- datetime -- so it's not obvious what you want to do. If you can't clearly describe the structure of the plot you intend to draw, it's doubtful that I or anyone else can help you. > > Best, > John > > John Fox, Professor Emeritus > McMaster University > Hamilton, Ontario, Canada > web: https://socialsciences.mcmaster.ca/jfox/ > <https://socialsciences.mcmaster.ca/jfox/> [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.