R help - Dec 2020 - How to specify year-month-day for a plot

Jim, Thank you!
The data set begins
gcdf<-read.table(text="2013-12-29 19.175
2014-01-20 10.072
2014-02-12 10.241
I note that data begins in 2013. But the plot command does not show this first
entry in 2013, and instead shows the second data pair as the first data pair. As
a consequence, plot does not show the first data pair for 2013, and begins in
2014.
Greg
> On Dec 16, 2020, at 1:08 AM, Jim Lemon <drjimlemon at gmail.com>
wrote:
> 
> Hi Greg,
> I think this does what you want:
> 
> gcdf$date<-as.Date(gcdf$date,"%Y-%m-%d")
>
grid_dates<-as.Date(paste(2014:2020,1,1,sep="-"),"%Y-%m-%d")
> plot(gcdf$date, gcdf$gallons, main="2014 Toyota 4Runner",
xlab="Date",
>
ylab="Gallons",type="l",col="blue",yaxt="n")
> abline(h=seq(4,20,by=2),lty=4)
> abline(v=grid_dates,lty=4)
> axis(side=2,at=seq(4,20,by=2))
> 
> Jim
> 
> On Wed, Dec 16, 2020 at 2:16 PM Gregory Coats <gregcoats at me.com>
wrote:
>> 
>> Jim, Thanks for your help with R.
>> Feeding into R the file R_plot_18.r yields for me, on my Mac,
R_plot_18.pdf. Success.
>> I used abline to draw a horizontal background grid, and then used axis
label to identify the values represented by the horizontal dashed background
lines.
>> abline (h=c(2,4,6,8,10,12,14,16,18,20,22,24), lty=4, lwd=1.0,
col="grey60")
>> Similarly, I would like to draw a dashed vertical background grid. But
it is unclear to me how to direct R to draw a vertical dashed background grid
because I am again baffled how to specify to R a date value such as 2018-10-20
@18:00. I welcome your guidance.
>> Greg
>> 
>> On Dec 13, 2020, at 10:58 PM, Jim Lemon <drjimlemon at gmail.com>
wrote:
>> 
>> Hi Gregory,
>> 
>> On Mon, Dec 14, 2020 at 12:34 PM Gregory Coats <gregcoats at
me.com> wrote:
>> 
>> ...
>> Is there a convenient way to tell R to interpret ?2020-12-13? as a
date?
>> 
>> Notice the as.Date command in the code I sent to you. this converts a
>> string to a date with a resolution of one day. If you want a higher
>> time resolution, use strptime or one of the other POSIX date
>> conversion functions.
>> 
>> Jim
	[[alternative HTML version deleted]]

I added a zero initial entry to the data set. Greg
gcdf<-read.table(text="2013-11-29 00.000
2013-12-29 19.175
2014-01-20 10.072
2014-02-12 10.241
2014-03-02 05.916
> On Dec 16, 2020, at 12:32 PM, Gregory Coats via R-help <r-help at
r-project.org> wrote:
> 
> Jim, Thank you!
> The data set begins
> gcdf<-read.table(text="2013-12-29 19.175
> 2014-01-20 10.072
> 2014-02-12 10.241
> I note that data begins in 2013. But the plot command does not show this
first entry in 2013, and instead shows the second data pair as the first data
pair. As a consequence, plot does not show the first data pair for 2013, and
begins in 2014.
> Greg
> 
>> On Dec 16, 2020, at 1:08 AM, Jim Lemon <drjimlemon at gmail.com>
wrote:
>> 
>> Hi Greg,
>> I think this does what you want:
>> 
>> gcdf$date<-as.Date(gcdf$date,"%Y-%m-%d")
>>
grid_dates<-as.Date(paste(2014:2020,1,1,sep="-"),"%Y-%m-%d")
>> plot(gcdf$date, gcdf$gallons, main="2014 Toyota 4Runner",
xlab="Date",
>>
ylab="Gallons",type="l",col="blue",yaxt="n")
>> abline(h=seq(4,20,by=2),lty=4)
>> abline(v=grid_dates,lty=4)
>> axis(side=2,at=seq(4,20,by=2))
>> 
>> Jim
>> 
>> On Wed, Dec 16, 2020 at 2:16 PM Gregory Coats <gregcoats at
me.com> wrote:
>>> 
>>> Jim, Thanks for your help with R.
>>> Feeding into R the file R_plot_18.r yields for me, on my Mac,
R_plot_18.pdf. Success.
>>> I used abline to draw a horizontal background grid, and then used
axis label to identify the values represented by the horizontal dashed
background lines.
>>> abline (h=c(2,4,6,8,10,12,14,16,18,20,22,24), lty=4, lwd=1.0,
col="grey60")
>>> Similarly, I would like to draw a dashed vertical background grid.
But it is unclear to me how to direct R to draw a vertical dashed background
grid because I am again baffled how to specify to R a date value such as
2018-10-20 @18:00. I welcome your guidance.
>>> Greg
>>> 
>>> On Dec 13, 2020, at 10:58 PM, Jim Lemon <drjimlemon at
gmail.com> wrote:
>>> 
>>> Hi Gregory,
>>> 
>>> On Mon, Dec 14, 2020 at 12:34 PM Gregory Coats <gregcoats at
me.com> wrote:
>>> 
>>> ...
>>> Is there a convenient way to tell R to interpret ?2020-12-13? as a
date?
>>> 
>>> Notice the as.Date command in the code I sent to you. this converts
a
>>> string to a date with a resolution of one day. If you want a higher
>>> time resolution, use strptime or one of the other POSIX date
>>> conversion functions.
>>> 
>>> Jim