Re: [Rd] Negative years with strptime?
On my earlier post I forgot to mention the sessionInfo()
R version 2.15.0 (2012-03-30)
Platform: i386-pc-mingw32/i386 (32-bit)
locale:
[1] LC_COLLATE=Portuguese_Portugal.1252
LC_CTYPE=Portuguese_Portugal.1252
[3] LC_MONETARY=Portuguese_Portugal.1252 LC_NUMERIC=C
[5] LC_TIME=Portuguese_Portugal.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
Rui Barradas
Em 11-07-2012 02:05, Winston Chang escreveu:
It looks different on my system (Mac, R 2.15.1)
seq(as.Date("-01-01"), length = 22, by = "-1 year")
[1] "-01-01" "-001-01-01" "-002-01-01" "-003-01-01" "-004-01-01"
[6] "-005-01-01" "-006-01-01" "-007-01-01" "-008-01-01" "-009-01-01"
[11] "-010-01-01" "-011-01-01" "-012-01-01" "-013-01-01" "-014-01-01"
[16] "-015-01-01" "-016-01-01" "-017-01-01" "-018-01-01" "-019-01-01"
[21] "-020-01-01" "-021-01-01"
So in addition to the issues with converting a negative-year string to a
Date, it looks like converting a negative date to a string with
as.character.Date() is probably also not consistent.
It certainly would be useful to have a way of handling dates with
negative years.
-Winston
On Tue, Jul 10, 2012 at 4:59 PM, Rui Barradas mailto:ruipbarra...@sapo.pt>> wrote:
Hello,
Is there a bug with negative dates? Just see:
seq(as.Date("-01-01"), length = 22, by = "-1 year")
[1] "-01-01" "000/-01-01" "000.-01-01" "000--01-01" "000,-01-01"
[6] "000+-01-01" "000*-01-01" "000)-01-01" "000(-01-01" "000'-01-01"
[11] "00/0-01-01" "00//-01-01" "00/.-01-01" "00/--01-01" "00/,-01-01"
[16] "00/+-01-01" "00/*-01-01" "00/)-01-01" "00/(-01-01" "00/'-01-01"
[21] "00.0-01-01" "00./-01-01"
See the year number: "after" the zero, i.e., downward from zero, the
printed character is '/' which happens to be the ascii character
before '0', and before it's '.', etc. This sequence gives the nine
ascii characters before zero as last digit of the year, then the
10th is '0' as (now) expected, then goes to the second digit, etc.
It seems to stop at the first 9, or else we would have some sort of
real problem.
Anyway, this doesn't look right.
Rui Barradas
Em 10-07-2012 22:17, Winston Chang escreveu:
Is there a way to make as.Date() and strptime() process strings with
negative years? It appears that Date objects can contain
negative years and
you can convert them to strings, but you can't convert them back
to Date
objects.
x <- as.Date(c("0001-01-24", "0500-01-24"))
as.character(x)
# "0001-01-24" "0500-02-02"
as.Date(as.character(x))
# "0001-01-24" "0500-01-24"
# Minus 391 days gives negative year
as.character(x - 391)
# "-001-12-30" "0498-12-29"
# Can't convert this string back to Date
as.Date(as.character(x - 391))
# Error during wrapup: character string is not in a standard
unambiguous
format
# as.Date.character uses strptime, so we can try using strptime
directly
strptime(as.character(x), "%Y-%m-%d")
# "0001-01-24" "0500-01-24"
strptime(as.character(x - 391), "%Y-%m-%d")
# NA "0498-12-29"
Thanks,
-Winston
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Re: [Rd] Negative years with strptime?
It looks different on my system (Mac, R 2.15.1)
seq(as.Date("-01-01"), length = 22, by = "-1 year")
[1] "-01-01" "-001-01-01" "-002-01-01" "-003-01-01" "-004-01-01"
[6] "-005-01-01" "-006-01-01" "-007-01-01" "-008-01-01" "-009-01-01"
[11] "-010-01-01" "-011-01-01" "-012-01-01" "-013-01-01" "-014-01-01"
[16] "-015-01-01" "-016-01-01" "-017-01-01" "-018-01-01" "-019-01-01"
[21] "-020-01-01" "-021-01-01"
So in addition to the issues with converting a negative-year string to a
Date, it looks like converting a negative date to a string with
as.character.Date() is probably also not consistent.
It certainly would be useful to have a way of handling dates with negative
years.
-Winston
On Tue, Jul 10, 2012 at 4:59 PM, Rui Barradas wrote:
> Hello,
>
> Is there a bug with negative dates? Just see:
>
> seq(as.Date("-01-01"), length = 22, by = "-1 year")
> [1] "-01-01" "000/-01-01" "000.-01-01" "000--01-01" "000,-01-01"
> [6] "000+-01-01" "000*-01-01" "000)-01-01" "000(-01-01" "000'-01-01"
> [11] "00/0-01-01" "00//-01-01" "00/.-01-01" "00/--01-01" "00/,-01-01"
> [16] "00/+-01-01" "00/*-01-01" "00/)-01-01" "00/(-01-01" "00/'-01-01"
> [21] "00.0-01-01" "00./-01-01"
>
> See the year number: "after" the zero, i.e., downward from zero, the
> printed character is '/' which happens to be the ascii character before
> '0', and before it's '.', etc. This sequence gives the nine ascii
> characters before zero as last digit of the year, then the 10th is '0' as
> (now) expected, then goes to the second digit, etc.
>
> It seems to stop at the first 9, or else we would have some sort of real
> problem.
>
> Anyway, this doesn't look right.
>
> Rui Barradas
> Em 10-07-2012 22:17, Winston Chang escreveu:
>
>> Is there a way to make as.Date() and strptime() process strings with
>> negative years? It appears that Date objects can contain negative years
>> and
>> you can convert them to strings, but you can't convert them back to Date
>> objects.
>>
>>
>> x <- as.Date(c("0001-01-24", "0500-01-24"))
>> as.character(x)
>> # "0001-01-24" "0500-02-02"
>> as.Date(as.character(x))
>> # "0001-01-24" "0500-01-24"
>>
>> # Minus 391 days gives negative year
>> as.character(x - 391)
>> # "-001-12-30" "0498-12-29"
>>
>> # Can't convert this string back to Date
>> as.Date(as.character(x - 391))
>> # Error during wrapup: character string is not in a standard unambiguous
>> format
>>
>>
>> # as.Date.character uses strptime, so we can try using strptime directly
>> strptime(as.character(x), "%Y-%m-%d")
>> # "0001-01-24" "0500-01-24"
>>
>> strptime(as.character(x - 391), "%Y-%m-%d")
>> # NA "0498-12-29"
>>
>>
>> Thanks,
>> -Winston
>>
>> [[alternative HTML version deleted]]
>>
>> __**
>> R-devel@r-project.org mailing list
>> https://stat.ethz.ch/mailman/**listinfo/r-devel
>>
>>
>
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Re: [Rd] Negative years with strptime?
?as.Date
Why would pre years be handled correctly? The help file
explicitly states that they likely will not.
Note:
The default formats follow the rules of the ISO 8601 international
standard which expresses a day as ‘"2001-02-03"’.
If the date string does not specify the date completely, the
returned answer may be system-specific. The most common behaviour
is to assume that a missing year, month or day is the current one.
If it specifies a date incorrectly, reliable implementations will
give an error and the date is reported as ‘NA’. Unfortunately
some common implementations (such as ‘glibc’) are unreliable and
guess at the intended meaning.
Years before 1CE (aka 1AD) will probably not be handled correctly.
On Tue, Jul 10, 2012 at 4:59 PM, Rui Barradas wrote:
> Hello,
>
> Is there a bug with negative dates? Just see:
>
> seq(as.Date("-01-01"), length = 22, by = "-1 year")
> [1] "-01-01" "000/-01-01" "000.-01-01" "000--01-01" "000,-01-01"
> [6] "000+-01-01" "000*-01-01" "000)-01-01" "000(-01-01" "000'-01-01"
> [11] "00/0-01-01" "00//-01-01" "00/.-01-01" "00/--01-01" "00/,-01-01"
> [16] "00/+-01-01" "00/*-01-01" "00/)-01-01" "00/(-01-01" "00/'-01-01"
> [21] "00.0-01-01" "00./-01-01"
>
> See the year number: "after" the zero, i.e., downward from zero, the printed
> character is '/' which happens to be the ascii character before '0', and
> before it's '.', etc. This sequence gives the nine ascii characters before
> zero as last digit of the year, then the 10th is '0' as (now) expected, then
> goes to the second digit, etc.
>
> It seems to stop at the first 9, or else we would have some sort of real
> problem.
>
> Anyway, this doesn't look right.
>
> Rui Barradas
> Em 10-07-2012 22:17, Winston Chang escreveu:
>
>> Is there a way to make as.Date() and strptime() process strings with
>> negative years? It appears that Date objects can contain negative years
>> and
>> you can convert them to strings, but you can't convert them back to Date
>> objects.
>>
>>
>> x <- as.Date(c("0001-01-24", "0500-01-24"))
>> as.character(x)
>> # "0001-01-24" "0500-02-02"
>> as.Date(as.character(x))
>> # "0001-01-24" "0500-01-24"
>>
>> # Minus 391 days gives negative year
>> as.character(x - 391)
>> # "-001-12-30" "0498-12-29"
>>
>> # Can't convert this string back to Date
>> as.Date(as.character(x - 391))
>> # Error during wrapup: character string is not in a standard unambiguous
>> format
>>
>>
>> # as.Date.character uses strptime, so we can try using strptime directly
>> strptime(as.character(x), "%Y-%m-%d")
>> # "0001-01-24" "0500-01-24"
>>
>> strptime(as.character(x - 391), "%Y-%m-%d")
>> # NA "0498-12-29"
>>
>>
>> Thanks,
>> -Winston
>>
>> [[alternative HTML version deleted]]
>>
>> __
>> R-devel@r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>
> __
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--
Jeffrey Ryan
jeffrey.r...@lemnica.com
www.lemnica.com
www.esotericR.com
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Re: [Rd] Negative years with strptime?
Hello,
Is there a bug with negative dates? Just see:
seq(as.Date("-01-01"), length = 22, by = "-1 year")
[1] "-01-01" "000/-01-01" "000.-01-01" "000--01-01" "000,-01-01"
[6] "000+-01-01" "000*-01-01" "000)-01-01" "000(-01-01" "000'-01-01"
[11] "00/0-01-01" "00//-01-01" "00/.-01-01" "00/--01-01" "00/,-01-01"
[16] "00/+-01-01" "00/*-01-01" "00/)-01-01" "00/(-01-01" "00/'-01-01"
[21] "00.0-01-01" "00./-01-01"
See the year number: "after" the zero, i.e., downward from zero, the
printed character is '/' which happens to be the ascii character before
'0', and before it's '.', etc. This sequence gives the nine ascii
characters before zero as last digit of the year, then the 10th is '0'
as (now) expected, then goes to the second digit, etc.
It seems to stop at the first 9, or else we would have some sort of real
problem.
Anyway, this doesn't look right.
Rui Barradas
Em 10-07-2012 22:17, Winston Chang escreveu:
Is there a way to make as.Date() and strptime() process strings with
negative years? It appears that Date objects can contain negative years and
you can convert them to strings, but you can't convert them back to Date
objects.
x <- as.Date(c("0001-01-24", "0500-01-24"))
as.character(x)
# "0001-01-24" "0500-02-02"
as.Date(as.character(x))
# "0001-01-24" "0500-01-24"
# Minus 391 days gives negative year
as.character(x - 391)
# "-001-12-30" "0498-12-29"
# Can't convert this string back to Date
as.Date(as.character(x - 391))
# Error during wrapup: character string is not in a standard unambiguous
format
# as.Date.character uses strptime, so we can try using strptime directly
strptime(as.character(x), "%Y-%m-%d")
# "0001-01-24" "0500-01-24"
strptime(as.character(x - 391), "%Y-%m-%d")
# NA "0498-12-29"
Thanks,
-Winston
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[Rd] Negative years with strptime?
Is there a way to make as.Date() and strptime() process strings with
negative years? It appears that Date objects can contain negative years and
you can convert them to strings, but you can't convert them back to Date
objects.
x <- as.Date(c("0001-01-24", "0500-01-24"))
as.character(x)
# "0001-01-24" "0500-02-02"
as.Date(as.character(x))
# "0001-01-24" "0500-01-24"
# Minus 391 days gives negative year
as.character(x - 391)
# "-001-12-30" "0498-12-29"
# Can't convert this string back to Date
as.Date(as.character(x - 391))
# Error during wrapup: character string is not in a standard unambiguous
format
# as.Date.character uses strptime, so we can try using strptime directly
strptime(as.character(x), "%Y-%m-%d")
# "0001-01-24" "0500-01-24"
strptime(as.character(x - 391), "%Y-%m-%d")
# NA "0498-12-29"
Thanks,
-Winston
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