[R] How to plot dates

[Sarah Goslee]

Hi,

It doesn't have anything to do with having a Mac - you have POSIX.

It's because something is wrong with your data import. Looking at the
head() output you provided, it looks like your data file does NOT have
a header, because there's no datetime column, and the column name is
actually X2021.03.11.10.00.0

So you specified a nonexistent column, and got a zero-length answer.

With correct specification, the as.POSIXct function works as expected on Mac:


myDat <- read.table(text =
"datetime
2021-03-11 10:00:00
2021-03-11 14:17:00
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",
sep = ",", header = TRUE)


myDat$datetime <- as.POSIXct(myDat$datetime, tz = "", format =
"%Y-%M-%d %H:%M:%OS")

Sarah

On Tue, Mar 16, 2021 at 9:26 AM Gregory Coats via R-help
<r-help using r-project.org> wrote:
>
> My computer is an Apple MacBook. I do not have POSIX.
> The command
> myDat$datetime <- as.POSIXct(myDat$datetime, tz = "", format = "%Y-%M-%d %H:%M:%OS")
> yields the error
> Error in `$<-.data.frame`(`*tmp*`, datetime, value = numeric(0)) :
>   replacement has 0 rows, data has 13
> Please advise, How to proceed?
> Greg Coats
>
> > library(ggplot2)
> > # Read a txt file on the Desktop, named "myDat.txt"
> > myDat <- read.delim("~/Desktop/myDat.txt", header = TRUE, sep = ",")
> > head(myDat)
>   X2021.03.11.10.00.00
> 1  2021-03-11 14:17:00
> 2  2021-03-12 05:16:46
> 3  2021-03-12 09:17:02
> 4  2021-03-12 13:31:43
> 5  2021-03-12 22:00:32
> 6  2021-03-13 09:21:43
> > # convert data to date time object
> > myDat$datetime <- as.POSIXct(myDat$datetime, tz = "", format = "%Y-%M-%d %H:%M:%OS")
> Error in `$<-.data.frame`(`*tmp*`, datetime, value = numeric(0)) :
>   replacement has 0 rows, data has 13
> >
>         [[alternative HTML version deleted]]
>
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-- 
Sarah Goslee (she/her)
http://www.numberwright.com