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plotting issue with timestamps

3 messages · Dhiren DSouza, Gabor Grothendieck, Spencer Graves

Original
Dhiren DSouza
# 
I have a dataset with transactions and a timestamp at which they occoured 
during a day.  The time stamp is in the format YYYY/MM/DD hh:mm:ss.  I would 
like to plot a timeseries of the transactions to see if there is a 
particular time in the day when there is a spike in transactions.  Ofcourse 
the YYYY/MM/DD can be dropped since I am monitoring activity for the day and 
the actual date is unimportant.

Can anyone give me some direction on this.  I could possibly build a 
frequency table but not sure how to plot against the timestamp in the format 
above.  Any help would be appreciated.

-Dhiren
Gabor Grothendieck
#
On 8/17/05, Dhiren DSouza <dhiren22 at hotmail.com> wrote:
Lets say your times are in a character vector tt.  (If the dates
are there too use substring to remove them.) Then convert them
to times class (of library chron) which will represent them
internally as a fraction of a day where the day starts at 0 and 
goes to 1 so that 0.5 is noon.  Since we want a more meaningful
axis do not use the automatic plot axis (xaxt = "n") and also
restrict the xaxis to the internval 0:1.  So that we can get
all the hours to fix reduce the size of the axis labels to 70%.
Then redraw it yourself with the hours labelled and add some 
light grey vertical lines if you like.

library(chron)
tt <- c("10:11:12", "09:10:11", "01:02:03")
tt.times <- times(tt)
plot(density(tt.times), xaxt = "n", xlim = 0:1, xlab = "Hour")
axis(1, 0:24/24, 0:24, cex.axis = 0.7)
abline(v = 0:24/24, col = "lightgrey")

See RNews 4/1 Help Desk article for more.
6 days later
Spencer Graves
# 
Have you considered the "zoo" package?  It has a "vignette" that I 
found very useful.  After 'install.packages("zoo")', try the following:

	  Zoo <- vignette("zoo")
	  print(Zoo)
# to open the narrative vignette in an Adobe Acrobat reader
	  edit(Zoo)
# to open a script file in RGui to make it easy for you
# to process the R commands line by line, edit them as you wish, etc.

#  If you use XEmacs, do NOT use "edit(Zoo)".  Instead do the following:

	  Stangle(Zoo$file)

# This will write the R commands to a file, which you can then open
# and process line by line as in RGui.

	  spencer graves
Dhiren DSouza wrote: