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Patrick Giraudoux

2021-Feb-22 14:26 UTC

[R] strptime, date and conversion of week number into POSIX

Dear all,

I have a trouble trying to convert dates? given in character to POSIX. 
The date is expressed as a year then the week number e.g. "2020-01" 
(first week of 2020). I thought is can be converted as following:

strptime(mydate,format="%Y-%W")

%W refering to the week of the year as decimal number (00?53) using 
Monday as the first day of week (and typically with the first Monday of 
the year as day 1 of week 1), as indicated in the doc.

However, I got this result, with the month fixed to 02 (february) and 
day 22 (only the year is? converted correctly):

strptime(mydate,format="%Y-%W") [1] "2020-02-22 CET"
"2020-02-22 CET"
"2020-02-22 CET" "2020-02-22 CET" [5] "2020-02-22
CET" "2020-02-22 CET"
"2020-02-22 CET" "2020-02-22 CET" [9] "2020-02-22
CET" "2020-02-22 CET"
"2020-02-22 CET" "2020-02-22 CET" [13] "2020-02-22
CET" "2020-02-22 CET"
"2020-02-22 CET" "2020-02-22 CET" [17] "2020-02-22
CET" "2020-02-22 CET"
"2020-02-22 CET" "2020-02-22 CET" [21] "2020-02-22
CET" "2020-02-22 CET"
"2020-02-22 CET" "2020-02-22 CET" [25] "2020-02-22
CET" "2020-02-22 CET"
"2020-02-22 CET" "2020-02-22 CET" [29] "2020-02-22
CET" "2020-02-22 CET"
"2020-02-22 CET" "2020-02-22 CET" [33] "2020-02-22
CET" "2020-02-22 CET"
"2020-02-22 CET" "2020-02-22 CET" [37] "2020-02-22
CET" "2020-02-22 CET"
"2020-02-22 CET" "2020-02-22 CET" [41] "2020-02-22
CET" "2020-02-22 CET"
"2020-02-22 CET" "2020-02-22 CET" [45] "2020-02-22
CET" "2020-02-22 CET"
"2020-02-22 CET" "2020-02-22 CET" [49] "2020-02-22
CET" "2020-02-22 CET"
"2020-02-22 CET" "2020-02-22 CET" [53] "2020-02-22
CET" "2021-02-22 CET"
"2021-02-22 CET" "2021-02-22 CET" [57] "2021-02-22
CET" "2021-02-22 CET"
"2021-02-22 CET"

You'll find below a dump of "mydate" you can copy and paster if
you need
a try

Any hint welcome...

Best,

Patrick

mydate <-
c("2020-01", "2020-02", "2020-03",
"2020-04", "2020-05", "2020-06",
"2020-07", "2020-08", "2020-09",
"2020-10", "2020-11", "2020-12",
"2020-13", "2020-14", "2020-15",
"2020-16", "2020-17", "2020-18",
"2020-19", "2020-20", "2020-21",
"2020-22", "2020-23", "2020-24",
"2020-25", "2020-26", "2020-27",
"2020-28", "2020-29", "2020-30",
"2020-31", "2020-32", "2020-33",
"2020-34", "2020-35", "2020-36",
"2020-37", "2020-38", "2020-39",
"2020-40", "2020-41", "2020-42",
"2020-43", "2020-44", "2020-45",
"2020-46", "2020-47", "2020-48",
"2020-49", "2020-50", "2020-51",
"2020-52", "2020-53", "2021-01",
"2021-02", "2021-03", "2021-04",
"2021-05", "2021-06")


	[[alternative HTML version deleted]]

Patrick Giraudoux

2021-Feb-22 15:15 UTC

head link

[R] strptime, date and conversion of week number into POSIX

Sorry to answer to myself, but the format was clearly incorrect in the 
previous post. It should read, refering to the 1th day of the week:

strptime(paste0(mydate,"-1"),format="%Y-%W-%u")

It converts better, but with a NA on week 53
> strptime(paste0(pays$year_week,"-1"),format="%Y-%W-%u")  [1] "2020-01-06 CET"  "2020-01-13 CET"  "2020-01-20
CET"  "2020-01-27 CET"
  [5] "2020-02-03 CET"  "2020-02-10 CET"  "2020-02-17
CET"  "2020-02-24 CET"
  [9] "2020-03-02 CET"  "2020-03-09 CET"  "2020-03-16
CET"  "2020-03-23 CET"
[13] "2020-03-30 CEST" "2020-04-06 CEST" "2020-04-13
CEST" "2020-04-20 CEST"
[17] "2020-04-27 CEST" "2020-05-04 CEST" "2020-05-11
CEST" "2020-05-18 CEST"
[21] "2020-05-25 CEST" "2020-06-01 CEST" "2020-06-08
CEST" "2020-06-15 CEST"
[25] "2020-06-22 CEST" "2020-06-29 CEST" "2020-07-06
CEST" "2020-07-13 CEST"
[29] "2020-07-20 CEST" "2020-07-27 CEST" "2020-08-03
CEST" "2020-08-10 CEST"
[33] "2020-08-17 CEST" "2020-08-24 CEST" "2020-08-31
CEST" "2020-09-07 CEST"
[37] "2020-09-14 CEST" "2020-09-21 CEST" "2020-09-28
CEST" "2020-10-05 CEST"
[41] "2020-10-12 CEST" "2020-10-19 CEST" "2020-10-26
CET"  "2020-11-02 CET"
[45] "2020-11-09 CET"  "2020-11-16 CET"  "2020-11-23
CET"  "2020-11-30 CET"
[49] "2020-12-07 CET"  "2020-12-14 CET"  "2020-12-21
CET"  "2020-12-28 CET"
[53] NA                "2021-01-04 CET"  "2021-01-11 CET" 
"2021-01-18 CET"
[57] "2021-01-25 CET"  "2021-02-01 CET"  "2021-02-08
CET"
Warning message:
In strptime(paste0(pays$year_week, "-1"), format =
"%Y-%W-%u") :
   (0-based) yday 369 in year 2020 is invalid


Any idea on how to handle this ?




Le 22/02/2021 ? 15:26, Patrick Giraudoux a ?crit?:>
> Dear all,
>
> I have a trouble trying to convert dates? given in character to POSIX. 
> The date is expressed as a year then the week number e.g.
"2020-01"
> (first week of 2020). I thought is can be converted as following:
>
> strptime(mydate,format="%Y-%W")
>
> %W refering to the week of the year as decimal number (00?53) using 
> Monday as the first day of week (and typically with the first Monday 
> of the year as day 1 of week 1), as indicated in the doc.
>
> However, I got this result, with the month fixed to 02 (february) and 
> day 22 (only the year is? converted correctly):
>
> strptime(mydate,format="%Y-%W") [1] "2020-02-22 CET"
"2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" [5] "2020-02-22
CET" "2020-02-22
> CET" "2020-02-22 CET" "2020-02-22 CET" [9]
"2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" "2020-02-22
CET" [13] "2020-02-22
> CET" "2020-02-22 CET" "2020-02-22 CET"
"2020-02-22 CET" [17]
> "2020-02-22 CET" "2020-02-22 CET" "2020-02-22
CET" "2020-02-22 CET"
> [21] "2020-02-22 CET" "2020-02-22 CET" "2020-02-22
CET" "2020-02-22
> CET" [25] "2020-02-22 CET" "2020-02-22 CET"
"2020-02-22 CET"
> "2020-02-22 CET" [29] "2020-02-22 CET" "2020-02-22
CET" "2020-02-22
> CET" "2020-02-22 CET" [33] "2020-02-22 CET"
"2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" [37] "2020-02-22
CET" "2020-02-22
> CET" "2020-02-22 CET" "2020-02-22 CET" [41]
"2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" "2020-02-22
CET" [45] "2020-02-22
> CET" "2020-02-22 CET" "2020-02-22 CET"
"2020-02-22 CET" [49]
> "2020-02-22 CET" "2020-02-22 CET" "2020-02-22
CET" "2020-02-22 CET"
> [53] "2020-02-22 CET" "2021-02-22 CET" "2021-02-22
CET" "2021-02-22
> CET" [57] "2021-02-22 CET" "2021-02-22 CET"
"2021-02-22 CET"
>
> You'll find below a dump of "mydate" you can copy and paster
if you
> need a try
>
> Any hint welcome...
>
> Best,
>
> Patrick
>
> mydate <-
> c("2020-01", "2020-02", "2020-03",
"2020-04", "2020-05", "2020-06",
> "2020-07", "2020-08", "2020-09",
"2020-10", "2020-11", "2020-12",
> "2020-13", "2020-14", "2020-15",
"2020-16", "2020-17", "2020-18",
> "2020-19", "2020-20", "2020-21",
"2020-22", "2020-23", "2020-24",
> "2020-25", "2020-26", "2020-27",
"2020-28", "2020-29", "2020-30",
> "2020-31", "2020-32", "2020-33",
"2020-34", "2020-35", "2020-36",
> "2020-37", "2020-38", "2020-39",
"2020-40", "2020-41", "2020-42",
> "2020-43", "2020-44", "2020-45",
"2020-46", "2020-47", "2020-48",
> "2020-49", "2020-50", "2020-51",
"2020-52", "2020-53", "2021-01",
> "2021-02", "2021-03", "2021-04",
"2021-05", "2021-06")
>

	[[alternative HTML version deleted]]

Bert Gunter

2021-Feb-22 16:04 UTC

head link

[R] strptime, date and conversion of week number into POSIX

I think the relevant info from ?strptime is:

"For strptime the input string need not specify the date completely: it is
assumed that unspecified seconds, minutes or hours are zero, and an
unspecified year, month or day is the current one. (However, if a month is
specified, the day of that month has to be specified by %d or %e since the
current day of the month need not be valid for the specified month.) Some
components may be returned as NA (but an unknown tzone component is
represented by an empty string)."

I think this means that your strings cannot be converted by strptime() as
essential info is missing. Input from those with more date-time expertise
on this point would be welcome, however.

Cheers,
Bert
Bert Gunter

"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Mon, Feb 22, 2021 at 6:27 AM Patrick Giraudoux <
patrick.giraudoux at univ-fcomte.fr> wrote:
> Dear all,
>
> I have a trouble trying to convert dates  given in character to POSIX.
> The date is expressed as a year then the week number e.g.
"2020-01"
> (first week of 2020). I thought is can be converted as following:
>
> strptime(mydate,format="%Y-%W")
>
> %W refering to the week of the year as decimal number (00?53) using
> Monday as the first day of week (and typically with the first Monday of
> the year as day 1 of week 1), as indicated in the doc.
>
> However, I got this result, with the month fixed to 02 (february) and
> day 22 (only the year is  converted correctly):
>
> strptime(mydate,format="%Y-%W") [1] "2020-02-22 CET"
"2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" [5] "2020-02-22
CET" "2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" [9] "2020-02-22
CET" "2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" [13] "2020-02-22
CET" "2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" [17] "2020-02-22
CET" "2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" [21] "2020-02-22
CET" "2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" [25] "2020-02-22
CET" "2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" [29] "2020-02-22
CET" "2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" [33] "2020-02-22
CET" "2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" [37] "2020-02-22
CET" "2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" [41] "2020-02-22
CET" "2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" [45] "2020-02-22
CET" "2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" [49] "2020-02-22
CET" "2020-02-22 CET"
> "2020-02-22 CET" "2020-02-22 CET" [53] "2020-02-22
CET" "2021-02-22 CET"
> "2021-02-22 CET" "2021-02-22 CET" [57] "2021-02-22
CET" "2021-02-22 CET"
> "2021-02-22 CET"
>
> You'll find below a dump of "mydate" you can copy and paster
if you need
> a try
>
> Any hint welcome...
>
> Best,
>
> Patrick
>
> mydate <-
> c("2020-01", "2020-02", "2020-03",
"2020-04", "2020-05", "2020-06",
> "2020-07", "2020-08", "2020-09",
"2020-10", "2020-11", "2020-12",
> "2020-13", "2020-14", "2020-15",
"2020-16", "2020-17", "2020-18",
> "2020-19", "2020-20", "2020-21",
"2020-22", "2020-23", "2020-24",
> "2020-25", "2020-26", "2020-27",
"2020-28", "2020-29", "2020-30",
> "2020-31", "2020-32", "2020-33",
"2020-34", "2020-35", "2020-36",
> "2020-37", "2020-38", "2020-39",
"2020-40", "2020-41", "2020-42",
> "2020-43", "2020-44", "2020-45",
"2020-46", "2020-47", "2020-48",
> "2020-49", "2020-50", "2020-51",
"2020-52", "2020-53", "2021-01",
> "2021-02", "2021-03", "2021-04",
"2021-05", "2021-06")
>
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at 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.
>
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R help - Feb 2021 - strptime, date and conversion of week number into POSIX

[R] strptime, date and conversion of week number into POSIX

[R] strptime, date and conversion of week number into POSIX

[R] strptime, date and conversion of week number into POSIX