I assume that this is a lattice problem. Replacing xyplot with plot and using all the same arguments there is no error.
On Mon, Feb 22, 2021 at 11:26 AM Laurent Rhelp <laurentrh...@free.fr> wrote: > > Dear R-Help-List, > > I have to process time series with a sampling frequency of 1 MHz. > I use the POSIXct format for the date-times with microsecond in a zoo > object and the xyplot.zoo function to do the graphs. > As I show in the below example I had a trouble to plot the labels on the > x-axis with an error message. I found a solution but I would like to > know if I miss something. > The link > https://stackoverflow.com/questions/7726034/how-r-formats-posixct-with-fractional-seconds > > helped me to understand how to print the POSIXct value to see the > microseconds thanks to the function myformat.POSIXct: > > myformat.POSIXct <- function(x, digits=6) > { > x2 <- round(unclass(x), digits) > attributes(x2) <- attributes(x) > x <- as.POSIXlt(x2,origin="1970-01-01",tz="GMT") > x$sec <- round(x$sec, digits) > format.POSIXlt(x, paste("%Y-%m-%d %H:%M:%OS",digits,sep=""),tz="GMT") > > } > > > ## The example giving the error message: > > library(lattice) > library(zoo) > > ## > options(digits = 16) # to see all the digits on the screen > options(digits.secs = 6) # to see the microseconds > # mock data > # a sine with a frequency f0 and two others with a delay > Fs <- 1e+6 # sampling frequency 1 MHz > Ts <- 1/Fs > # frequency of the sinus > f0 <- 100000 > t0 <- 1/f0 > time <- seq(0, length = 1000, by = Ts) > A1 <- 1 > y1 <- A1 * sin(2*pi*f0*time) > y2 <- 2 * A1 * sin(2*pi*f0*(time+0.000002)) > y3 <- 3 * A1 * sin(2*pi*f0*(time+0.000005)) > ## creation of a dataframe: > ## > DF <- data.frame( time = time, y1 = y1, y2 = y2, y3 = y3) > # Since I want to allow for the datetime POSIXct format on the x-axis > # for the plot I transform my dataframe in a zoo object > # > # say that my acquisition began at "2021-02-08 09:15:50.000000" > # > mystart <- as.POSIXct("2021-02-08 09:15:50.000000", format = "%Y-%m-%d > %H:%M:%OS",tz="GMT") > mystart > # To see the correct datetime I use the myformat.POSIXct function > myformat.POSIXct(mystart) > ## > ## using the method seq.POSIXct as following doesn't work: > ## mydatetime <- seq( mystart , length = nrow(DF), by = "0.000001 sec") > ## head( myformat.POSIXct(mydatetime) ) > ## if I use the following command it works: > mydatetime <- seq( mystart , length = nrow(DF), by = 0.000001) > head( myformat.POSIXct(mydatetime) ) > ## I do the zoo object: > DF.z <- zoo(DF[,-1],order.by = mydatetime) > ## We don't see the correct value for the index: > head(DF.z) > # time y1 y2 y3 > # 2021-02-08 09:15:50.000000 0e+00 0.000000000000000e+00 > 1.902113032590307e+00 3.673819061467132e-16 > # 2021-02-08 09:15:50.000000 1e-06 5.877852522924730e-01 > 1.902113032590307e+00 -1.763355756877419e+00 > # 2021-02-08 09:15:50.000001 2e-06 9.510565162951535e-01 > 1.175570504584947e+00 -2.853169548885460e+00 > # 2021-02-08 09:15:50.000003 3e-06 9.510565162951536e-01 > 1.133099690464601e-15 -2.853169548885460e+00 > # 2021-02-08 09:15:50.000004 4e-06 5.877852522924736e-01 > -1.175570504584946e+00 -1.763355756877420e+00 > # 2021-02-08 09:15:50.000005 5e-06 5.665498452323003e-16 > -1.902113032590306e+00 -3.399299071393802e-15 > # If I use myformat.POSIXct I see that the index is correct in the > object DF: > head(myformat.POSIXct(index(DF.z))) > ## and when I plot I have an error: > xyplot( DF.z > , screens = c(1,1,1) > , type = "l" > , col = c("red","blue","black") > > ) > > # Error in prettyDate_TMP(x, ...) : range too small for min.n > > # if I process by hand the plot of the labels on the x-axis it works: > # > myend <- tail(mydatetime,1) > > myticks <- seq( mystart , to = myend , length = 5) > mylabels <- format(myticks,"%H:%M:%OS") > > xyplot( DF.z > , screens = c(1,1,1) > , type = "l" > , col = c("red","blue","black") > , scales = list( > y= list(relation = "free", abbreviate=TRUE), > x = list( at = myticks, labels = mylabels > , rot = 45, cex = 0.5) > ) > ) > # The microseconds are well taken into account with the window function > # if I want to plot only 100 microseconds but there is of course the same > # trouble for the plot > > myend <- as.POSIXct("2021-02-08 09:15:50.000100", format = "%Y-%m-%d > %H:%M:%OS",tz="GMT") > myformat.POSIXct(myend) > > DF.w <- window( DF.z ,start = mystart, end = myend) > > myticks <- seq( mystart , to = myend , length = 5) > mylabels <- format(myticks,"%H:%M:%OS") > > xyplot( DF.w > , screens = c(1,1,1) > , type = "l" > , col = c("red","blue","black") > ) > > ## Error in prettyDate_TMP(x, ...) : range too small for min.n > > xyplot( DF.w > , screens = c(1,1,1) > , type = "l" > , col = c("red","blue","black") > , scales = list( > y= list(relation = "free", abbreviate=TRUE), > x = list( at = myticks, labels = mylabels > , rot = 45, cex = 0.5) > ) > ) > > May you please tell me if I miss something in the way to use POSIXct > with microseconds in a zoo object ? > > Thank you > Laurent > > > > > > > -- > L'absence de virus dans ce courrier électronique a été vérifiée par le > logiciel antivirus Avast. > https://www.avast.com/antivirus > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
