[R] How to specify year-month-day for a plot

[Gregory Coats]

Hi Jim,
Thank you VERY much!
In what I tried, my values for the vertical Y were automatically understood by R.
But it appears that the string yyyy-mm-dd was NOT recognized by R as a date for the X axis, and gave a red error message.
My values for Year-Month-Day were NOT understood by R.
Is there a convenient way to tell R to interpret “2020-12-13” as a date?

data <- data.frame(
  day = as.Date("2020-02-15", "2020-03-10", "2020-05-04", "2020-06-21", "2020-08-01", "2020-08-27", "2020-09-28", "2020-11-09", "2020-12-11")
  value = (15.973, 18.832, 17.392, 14.774, 19.248, 14.913, 15.226, 14.338, 18.777, 19.652))
p <- ggplot(data, aes(x=day, y=value))
  geom_line()
  xlab("X Label")
p
Error: unexpected symbol in:
"  day = as.Date("2020-02-15", "2020-03-10", "2020-05-04", "2020-06-21", "2020-08-01", "2020-08-27", "2020-09-28", "2020-11-09", "2020-12-11")
  value"

Greg Coats
gregcoats using me.com
Reston, Virginia USA

> On Dec 13, 2020, at 5:42 PM, Jim Lemon <drjimlemon using gmail.com> wrote:
> 
> Hi Gregory,
> Here's a start:
> 
> gcdf<-read.table(text="2020-01-05 15.973
> 2020-02-15 18.832
> 2020-03-10 17.392
> 2020-05-04 14.774
> 2020-06-21 19.248
> 2020-08-01 14.913
> 2020-08-27 15.226
> 2020-09-28 14.338
> 2020-11-09 18.777
> 2020-12-11 19.652",
> header=TRUE,stringsAsFactors=FALSE,
> col.names=c("date","gallons"))
> gcdf$date<-as.Date(gcdf$date,"%Y-%m-%d")
> plot(gcdf$date,gcdf$gallons,main="Gallons by date",
> xlab="Date",ylab="Gallons")
> 
> Jim
> 
> On Mon, Dec 14, 2020 at 9:33 AM Gregory Coats via R-help
> <r-help using r-project.org> wrote:
>> 
>> Starting with year-month-day, for the variable gallons, I can easily plot the variable gallons, while disregarding the date.
>> gallons <- c (15.973, 18.832, 17.392, 14.774, 19.248, 14.913, 15.226, 14.338, 18.777, 19.652)
>> plot (gallons, type="l", xlab="X label", ylab="Y label", col="blue”)
>> 
>> How do I direct R to plot the variable gallons, at the appropriate, irregularly-spaced places on the X axis, while paying attention to the year-month-day?
>> 
>> format = "%Y-%m-%d”
>> 2020-01-05 15.973
>> 2020-02-15 18.832
>> 2020-03-10 17.392
>> 2020-05-04 14.774
>> 2020-06-21 19.248
>> 2020-08-01 14.913
>> 2020-08-27 15.226
>> 2020-09-28 14.338
>> 2020-11-09 18.777
>> 2020-12-11 19.652
>>        [[alternative HTML version deleted]]
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