[R] How to plot dates

[Gregory Coats]

I want to plot the date and time of the event, as reflected in data.
2021-03-11 10:00:00
Greg Coats

> On Mar 16, 2021, at 2:23 PM, Jeff Newmiller <jdnewmil using dcn.davis.ca.us> wrote:
> 
> You don't seem to have a Y_Var in your data. What is it that you want to plot?
> 
> On March 16, 2021 9:21:05 AM PDT, Gregory Coats via R-help <r-help using r-project.org> wrote:
>> Sarah, Thank you. Yes, now as.POSIXct works.
>> But the ggplot command I was told to use yields an Error message, and
>> there is no output plot.
>> Please help me. Greg
>>> library(ggplot2)
>>> 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)
>>> head(myDat)
>>            datetime
>> 1 2021-03-11 10:00:00
>> 2 2021-03-11 14:17:00
>> 3 2021-03-12 05:16:46
>> 4 2021-03-12 09:17:02
>> 5 2021-03-12 13:31:43
>> 6 2021-03-12 22:00:32
>>> myDat$datetime <- as.POSIXct(myDat$datetime, tz = "", format
>> ="%Y-%M-%d %H:%M:%OS”)
>>> ggplot(myDat, aes(x=datetime, y = Y_Var)) + geom_point()
>> Error in FUN(X[[i]], ...) : object 'Y_Var' not found
>> 
>>> On Mar 16, 2021, at 9:36 AM, Sarah Goslee <sarah.goslee using gmail.com>
>> wrote:
>>> 
>>> 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]]
>>>> ______________________________________________
>>>> R-help using 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.
>>> -- 
>>> Sarah Goslee (she/her)
>>> http://www.numberwright.com
>> 
>> 
>> 	[[alternative HTML version deleted]]
>> 
>> ______________________________________________
>> R-help using 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.
> 
> -- 
> Sent from my phone. Please excuse my brevity.