Re: [R] How to plot dates

Rui Barradas Tue, 16 Mar 2021 13:16:39 -0700

Hello,

I don't really understand what is to be plotted, just the time of theevent? But what event?


Anyway, with the data read with Sarah's code, maybe


library(ggplot2)

ggplot(myDat, aes(x = datetime, y = 1)) +
  geom_linerange(aes(ymin = 0, ymax = 1), linetype = "dotted") +
  geom_point() +
  scale_x_datetime(breaks = myDat$datetime) +
  scale_y_continuous(labels = NULL) +
  ylab("event") +
  theme(axis.text.x = element_text(angle = 60, vjust = 1, hjust=1),
        axis.ticks.y = element_blank())


Hope this helps,

Rui Barradas

Às 13:36 de 16/03/21, Sarah Goslee escreveu:

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@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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and provide commented, minimal, self-contained, reproducible code.

Re: [R] How to plot dates

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