[R] How to plot dates

[Jeff Newmiller]

So what do you want quantity on the y-axis to be?

On March 16, 2021 11:45:32 AM PDT, Gregory Coats <gregcoats using me.com> wrote:
>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.

-- 
Sent from my phone. Please excuse my brevity.