R help - Feb 2012 - strange behaviour of "POSIXlt" "POSIXt" object

Hi, 
Does anybody know why get I this kind of strange situation:

Browse[2]> hcEnd
[1] "2009-03-29 06:30:00"
Browse[2]> class(hcEnd)
[1] "POSIXlt" "POSIXt" 
Browse[2]> is.na(hcEnd)
[1] TRUE

This issue is the source of my all issues in my program, 

Thanks for your help

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Can you dput(hcEnd) and give a snippet of the code that generates it?

Michael

On Feb 24, 2012, at 12:57 PM, ikuzar <razuki at hotmail.fr> wrote:
> Hi, 
> Does anybody know why get I this kind of strange situation:
> 
> Browse[2]> hcEnd
> [1] "2009-03-29 06:30:00"
> Browse[2]> class(hcEnd)
> [1] "POSIXlt" "POSIXt" 
> Browse[2]> is.na(hcEnd)
> [1] TRUE
> 
> This issue is the source of my all issues in my program, 
> 
> Thanks for your help
> 
> --
> View this message in context:
http://r.789695.n4.nabble.com/strange-behaviour-of-POSIXlt-POSIXt-object-tp4418115p4418115.html
> Sent from the R help mailing list archive at Nabble.com.
> 
> ______________________________________________
> R-help at r-project.org mailing list
> 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.

> Does anybody know why get I this kind of strange situation:
> 
> Browse[2]> hcEnd
> [1] "2009-03-29 06:30:00"
> Browse[2]> class(hcEnd)
> [1] "POSIXlt" "POSIXt" 
> Browse[2]> is.na(hcEnd)
> [1] TRUE
pp<-as.POSIXlt("2009-03-29 06:30:00")
pp
[1] "2009-03-29 06:30:00"
class(pp)
[1] "POSIXlt" "POSIXt" 
is.na(pp)
[1] FALSE

So we can't repeat your example.

-- 
Curt Seeliger, Data Ranger
Raytheon Information Services - Contractor to ORD
seeliger.curt@epa.gov
541/754-4638



	[[alternative HTML version deleted]]

What version of R are you using.  Here is the results with 2.14.1 under
Windows:
> x <- as.POSIXlt("2009-03-29 06:30:00")
>
> x
[1] "2009-03-29 06:30:00"
> class(x)
[1] "POSIXlt" "POSIXt"
> is.na(x)
[1] FALSE
>

On Fri, Feb 24, 2012 at 12:57 PM, ikuzar <razuki@hotmail.fr> wrote:
> Hi,
> Does anybody know why get I this kind of strange situation:
>
> Browse[2]> hcEnd
> [1] "2009-03-29 06:30:00"
> Browse[2]> class(hcEnd)
> [1] "POSIXlt" "POSIXt"
> Browse[2]> is.na(hcEnd)
> [1] TRUE
>
> This issue is the source of my all issues in my program,
>
> Thanks for your help
>
> --
> View this message in context:
>
http://r.789695.n4.nabble.com/strange-behaviour-of-POSIXlt-POSIXt-object-tp4418115p4418115.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@r-project.org mailing list
> 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.
>


-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.

	[[alternative HTML version deleted]]

Hi, 

I do not know what part of my code should I post here (I use large size of
data, the loop "for" contains many lines). The situation is difficult
to
post here, but I hope these lines would be useful for help:

hcEndDateTmp = userDateStart
  if((hcStartTime<="23:59") & (hcEndTime >=
"00:00")){
    hcEndDateTmp$mday = userDateStart$mday + 1
  }
  hcEndDate = strftime(hcEndDateTmp, "%Y-%m-%d")
  hcStart = ""
hcEnd = as.POSIXlt(paste(hcEndDate, hcEndTime))

for(rowNum in 1:nbJour){
    ...
    hcStart = as.POSIXlt(ecs$startAt[[rowNum]])
    ecsInterval2
datePower[(datePower$DateTime>=hcStart)&(datePower$DateTime<=hcEnd), ]
    ...
   hcEnd$mday = hcEnd$mday + 1
  cat("DEBUG: rowNum=", rowNum, "is.na(hcEnd)=",
is.na(hcEnd), "\n")
}

the two last lines are very important. It yields:

DEBUG: rowNum= 1 is.na(hcEnd)= FALSE 
DEBUG: rowNum= 2 is.na(hcEnd)= FALSE 
DEBUG: rowNum= 3 is.na(hcEnd)= FALSE 
DEBUG: rowNum= 4 is.na(hcEnd)= FALSE 
DEBUG: rowNum= 5 is.na(hcEnd)= FALSE 
DEBUG: rowNum= 6 is.na(hcEnd)= FALSE 
DEBUG: rowNum= 7 is.na(hcEnd)= TRUE 

Browse[1]> hcEnd
[1] "2009-03-29 06:30:00"
Browse[1]> class(hcEnd)
[1] "POSIXlt" "POSIXt" 

So, At the end of 7th iteration, hcEnd becomes NA (I guess because of
hcEnd$mday = hcEnd$mday + 1 ?!?). But It remains strange because the class
of hcEnd is here "POSIXlt" "POSIXt" (it should be
"logical".!! Am I
wrong???)

Here is the version of R:
platform       i386-pc-mingw32              
arch           i386                         
os             mingw32                      
system         i386, mingw32                
status                                      
major          2                            
minor          13.2                         
year           2011                         
month          09                           
day            30                           
svn rev        57111                        
language       R                            
version.string R version 2.13.2 (2011-09-30)

thanks for your help

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is.na(POSIXltObject) can behave oddly if you manipulate
the fields of the POSIXlt object directly so as to
cause illegal combinations of values.  E.g., the 35th
of February, 2009, is not considered an NA but the 36th
and above are:

  > z <- as.POSIXlt("2009-02-25 06:30:00")
  > for(i in 1:20){ z$mday <- z$mday + 1L ; cat(is.na(z), ":
");print(z)}
  FALSE : [1] "2009-02-26 06:30:00"
  FALSE : [1] "2009-02-27 06:30:00"
  FALSE : [1] "2009-02-28 06:30:00"
  FALSE : [1] "2009-03-01 06:30:00"
  FALSE : [1] "2009-03-02 06:30:00"
  FALSE : [1] "2009-03-03 06:30:00"
  FALSE : [1] "2009-03-04 06:30:00"
  FALSE : [1] "2009-03-05 06:30:00"
  FALSE : [1] "2009-03-06 06:30:00"
  FALSE : [1] "2009-03-07 06:30:00"
  TRUE : [1] "2009-03-08 06:30:00"
  TRUE : [1] "2009-03-09 06:30:00"
  TRUE : [1] "2009-03-10 06:30:00"
  TRUE : [1] "2009-03-11 06:30:00"
  TRUE : [1] "2009-03-12 06:30:00"
  TRUE : [1] "2009-03-13 06:30:00"
  TRUE : [1] "2009-03-14 06:30:00"
  TRUE : [1] "2009-03-15 06:30:00"
  TRUE : [1] "2009-03-16 06:30:00"
  TRUE : [1] "2009-03-17 06:30:00"

The print routine does not seem to consult is.na().

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com 
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at
r-project.org] On Behalf Of ikuzar
> Sent: Monday, February 27, 2012 2:41 AM
> To: r-help at r-project.org
> Subject: Re: [R] strange behaviour of "POSIXlt"
"POSIXt" object
> 
> Hi,
> 
> I do not know what part of my code should I post here (I use large size of
> data, the loop "for" contains many lines). The situation is
difficult to
> post here, but I hope these lines would be useful for help:
> 
> hcEndDateTmp = userDateStart
>   if((hcStartTime<="23:59") & (hcEndTime >=
"00:00")){
>     hcEndDateTmp$mday = userDateStart$mday + 1
>   }
>   hcEndDate = strftime(hcEndDateTmp, "%Y-%m-%d")
>   hcStart = ""
> hcEnd = as.POSIXlt(paste(hcEndDate, hcEndTime))
> 
> for(rowNum in 1:nbJour){
>     ...
>     hcStart = as.POSIXlt(ecs$startAt[[rowNum]])
>     ecsInterval2 >
datePower[(datePower$DateTime>=hcStart)&(datePower$DateTime<=hcEnd), ]
>     ...
>    hcEnd$mday = hcEnd$mday + 1
>   cat("DEBUG: rowNum=", rowNum, "is.na(hcEnd)=",
is.na(hcEnd), "\n")
> }
> 
> the two last lines are very important. It yields:
> 
> DEBUG: rowNum= 1 is.na(hcEnd)= FALSE
> DEBUG: rowNum= 2 is.na(hcEnd)= FALSE
> DEBUG: rowNum= 3 is.na(hcEnd)= FALSE
> DEBUG: rowNum= 4 is.na(hcEnd)= FALSE
> DEBUG: rowNum= 5 is.na(hcEnd)= FALSE
> DEBUG: rowNum= 6 is.na(hcEnd)= FALSE
> DEBUG: rowNum= 7 is.na(hcEnd)= TRUE
> 
> Browse[1]> hcEnd
> [1] "2009-03-29 06:30:00"
> Browse[1]> class(hcEnd)
> [1] "POSIXlt" "POSIXt"
> 
> So, At the end of 7th iteration, hcEnd becomes NA (I guess because of
> hcEnd$mday = hcEnd$mday + 1 ?!?). But It remains strange because the class
> of hcEnd is here "POSIXlt" "POSIXt" (it should be
"logical".!! Am I
> wrong???)
> 
> Here is the version of R:
> platform       i386-pc-mingw32
> arch           i386
> os             mingw32
> system         i386, mingw32
> status
> major          2
> minor          13.2
> year           2011
> month          09
> day            30
> svn rev        57111
> language       R
> version.string R version 2.13.2 (2011-09-30)
> 
> thanks for your help
> 
> --
> View this message in context:
http://r.789695.n4.nabble.com/strange-behaviour-of-POSIXlt-POSIXt-
> object-tp4418115p4424214.html
> Sent from the R help mailing list archive at Nabble.com.
> 
> ______________________________________________
> R-help at r-project.org mailing list
> 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.

So, how is the correct way to increment the day ?

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