How to plot dates

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 at 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 at 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

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