R help - May 2018 - Adding Year-Month-Day to X axis

Jim,
That you very much!
How do I instruct staxlab to label once every n days, rather than labeling every
day?
Greg
> On May 5, 2018, at 6:50 PM, Jim Lemon <drjimlemon at gmail.com>
wrote:
> 
> staxlab(1,at=x_yyyymmdd,labels=format(x_yyyymmdd,"%Y-%m-%d"))

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Hi Greg,
By default, the "axis" function puts the labels on one line and drops
labels that would overlap. When you have labels that are all the same
length, this usually results in every second, or third, or fourth
label being displayed. So you can probably get what you want by not
using staxlab. However, if you really want to use staxlab, try this:

oddones<-seq(1,length(x_yyyymmdd)-1,by=2)
staxlab(1,at=x_yyyymmdd[oddones],
 labels=format(x_yyyymmdd,"%Y-%m-%d")[oddones])

It will also work with plain "axis", which is what you seem to want.

Jim

Jim,
Thank you very much!
How do I use the axis command for side=1 to label the x horizontal axis, in the
format="%Y-%m-%d? style?
Greg

y_duration <- c (301.59050,  387.35700,  365.64366,  317.26150,  321.71883, 
342.44950,  318.95350,  322.33233,  330.60333,  428.99516,  297.82066, 
258.23166)
x_yyyymmdd <-as.Date(c ("2018-04-25", "2018-04-26",
"2018-04-27", "2018-04-28", "2018-04-29",
"2018-04-30", "2018-05-01", "2018-05-02",
"2018-05-03", "2018-05-04", "2018-05-05",
"2018-05-06"), format="%Y-%m-%d")
plot   (x_yyyymmdd, y_duration, type="l", xaxt="n",
yaxt="n", ylim=range(240,480))
abline (h=c(240,270,300,330,360,390,420,450,480,510,540), lty=2, lwd=1.0,
col="grey40")
axis   (side=2, at=240,  cex.axis=1.0, label="4:00")
axis   (side=2, at=300,  cex.axis=1.0, label="5:00")
axis   (side=2, at=360,  cex.axis=1.0, label="6:00")
axis   (side=2, at=420,  cex.axis=1.0, label="7:00")
axis   (side=2, at=480,  cex.axis=1.0, label="8:00")
> On May 6, 2018, at 3:52 AM, Jim Lemon <drjimlemon at gmail.com>
wrote:
> 
> Hi Greg,
> By default, the "axis" function puts the labels on one line and
drops
> labels that would overlap. When you have labels that are all the same
> length, this usually results in every second, or third, or fourth
> label being displayed. So you can probably get what you want by not
> using staxlab. However, if you really want to use staxlab, try this:
> 
> oddones<-seq(1,length(x_yyyymmdd)-1,by=2)
> staxlab(1,at=x_yyyymmdd[oddones],
> labels=format(x_yyyymmdd,"%Y-%m-%d")[oddones])
> 
> It will also work with plain "axis", which is what you seem to
want.
> 
> Jim

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