similar to: POSIXct dates on x-axis using xyplot

I am using POSIXct objects to store my date/time information. If I am plotting less that 2 days worth of data, I get the correct tick marks on the x-axis which is showing the 'day HH:MM' and these line up with the data points. If the data spans more than 2 days, the tick marks are now off. In the data below, I am creating some sample data and plotting the points. I am in the Eastern

A newbie here - please forgive me if this is a basic question. We have an in house package built in R 2.2.1 (yes we're a little behind the times at our firm)and would like to rebuild it using R 2.5.1. However, when I try and build the package from source, I keep getting this error: Error in as(slotVal, slotClass, strict = FALSE) : no method or default for coercing "POSIXt"

I rarely work with dates in R, so I know very little about the POSIXct and POSIXlt classes. I'm importing an excel file into R using the RODBC package, and am having issues reformatting the dates. 1. The important info: > sessionInfo() R version 2.12.2 (2011-02-25) Platform: i386-pc-mingw32/i386 (32-bit) locale: [1] LC_COLLATE=English_United States.1252 LC_CTYPE=English_United

I have a series of datasets, each containing pH measurements and manufacturing dates, and each dataset pertains to a different manufactured product. I'm trying to create a series of plots of pH measurements by date, but the default X-axis labeling behavior is not giving adequate results in this particular case, and I can't figure out how to persuade R to come up with something more

Running under Windows XP 64 bit, as.POSIXlt()/as.POSIXct() seem to think that US time zones (EST5EDT, MST7MDT) switched from daylight savings back to standard time on Oct 28, 2007, whereas the switch is actually on Sun Nov 04, 2007. Examples: > Sys.timezone() [1] "Mountain Daylight Time" > as.POSIXct("2007-10-30 12:38:47") [1] "2007-10-30 12:38:47 Mountain

I have encountered the following behaviour in lattice in 2.6.1 (and 2.4.0) which differs depending upon the type you use. I believe the numeric behaviour to be correct, and the POSIXct behaviour to be in error. When the x data and x axis in a lattice graph are POSIXct, and when using scales$x$at and scales$x$labels to add custom labels: If the first visible at value is not the first

I am a bit confused about how to get the format of the labels in xyplot to show as dates rather than the numeric value. e.g., x <- as.Date(c("20/01/2001","20/02/2003","21/06/2004"),"%d/%m/%Y") y <- c(1,2,3) plot(y~x) #produces formatted labels xyplot(y~x) #doesn't give formatted x labels

xyplot doesn't seem to want to label my x-axis with dates but instead puts the day-number for each date. begdate is the number of days since January 1, 1960 and was initially created by library(date) ... polls$begdate<-mdy.date(begmm,begdd,begyy) I create a new dataframe (pollstack) which includes begdate. In the process begdate seems to lose its date attribute so I redo it as: >

Hi R-devel. I've noticed a couple of quirks in the current time/date axis functions (axis.Date, axis.POSIXct, and the equivalents in lattice). Looking at the code, it seems like a fairly ad-hoc approach, often using pretty() on components of the time. This is not always ideal - for example a one-hour interval gets cut into 10-minute chunks rather than the more natural 15-minute chunks (since

Dear R-helpers, I have a problem converting an object made with the 'chron' function to a POSIXct object: # Make date based on DOY dat <- chron(dates=232, origin.=c(month=1, day=1, year=2008)) dat #[1] 08/20/08 # Converting to POSIXct uses current timezone (Sydney): as.POSIXct(dat) #[1] "2008-08-20 10:00:00 EST" # Setting GMT timezone has no effect? as.POSIXct(dat,

Hi: I do not understand the returned value of NA in the following, which is a simplified version of my attempt to convert the start column of the data frame AirQual in the SwissAir package. as.POSIXct(paste('04.04.2004 0',0:3,sep=''),format='%d.%m.%Y %H') [1] "2004-04-04 00:00:00 EST" "2004-04-04 01:00:00 EST" [3] NA

Hi, I'm trying to do something simple (I think) with lattice graphics. I want to have three xyplots in a single column, where the x axis for the three is a date range and the y axes are numeric. I tried doing the first chart, and ran into a problem. When I enter: xyplot (date ~ count) I get a well formed plot with the date on the y axis, but when I enter: xyplot (count ~ date) I get:

Dear R People: Here is an interesting question: >library(chron) >xt <- seq.dates(from="01/01/2004",by="days",length=5) >xt [1] 01/01/04 01/02/04 01/03/04 01/04/04 01/05/04 > #Fine so far >as.POSIXct(xt) [1] "2003-12-31 18:00:00 Central Standard Time" [2] "2004-01-01 18:00:00 Central Standard Time" [3] "2004-01-02 18:00:00 Central

When plotting a reversed time axis with the base graphics system, R fails to label the axes. Example: times <- c(Sys.time() - 100, Sys.time()) plot(times, 1:2, xlim = times) # correctly labels the x-axis plot(times, 1:2, xlim = rev(times)) # fails to label the x-axis axis.POSIXct(1, times) # still fails to add labels dates <- c(Sys.Date() - 10, Sys.Date()) plot(dates, 1:2, xlim = dates)

I'm trying to produce a barchart plot with groups, in which each group is placed in a particular time scale in x-axis. If I use barchart directly it does not take the time scale. I've tried with xyplot and adding a panel.barchart, I have the bars in the right place, but not the three groups I'm trying to produce. I've tried defining panel and panel.group, but can't get it to

I noticed the addition of the Dates class for dates without times, in R 1.9. I am making extensive use of POSIXct at present and would like to know whether it is worth changing to Dates. What are a few of the trade-offs? Thanks, Frank --- Frank E Harrell Jr Professor and Chair School of Medicine Department of Biostatistics Vanderbilt University

Some time ago, I posted a note about what I considered to be a bug in axis.POSIXt() for R 2.8.x, relating to whether timezones in the data are obeyed on the axes. A link to that note, and to a quick and helpful response, is at the following URL http://www.nabble.com/patch-for-axis.POSIXct-%28related-to-timezones%29-td22338700.html#a22338700 Note that R 2.9.0 has been adjusted to help with

The following code: cut(as.POSIXct("2009-11-01 04:00:00", tz="America/Los_Angeles"), "1 day") gives the error: Error in seq.int(0, to - from, by) : 'to' must be finite This is related to November 1st, 2009 being the switchover date from daylight savings time to standard time in the America/Los_Angeles time zone. In particular, in cut.POSIXt, the starting

I am finding that axis.POSIXct uses the local timezone for deciding where to put tic marks, even if the data being plotted are in another time zone. The solution is to use attr() to copy from the 'x' (provided as an argument) to the 'z' (used for the 'at' locations). I have pasted my proposed solution in section 1 below (as a diff). Then, in section 2, I'll put some

Prof. Ripley has provided very helpful information regarding X-axis labeling with POSIXct-class dates. Now I've run into another bit of problematic behavior. I'm running R 1.3.0 on Windows NT 4.0. When I create a plot with the optional argument xaxt = "n", and the X axis is generated from dates of class POSIXct, the X axis is plotted. Obviously, I'd like to prevent the X