Query about use of format in strptime

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Query about use of format in strptime

Stefano Sofia
Dear R-list users,
I need to use strptime because I have to deal with date with hours and minutes.
I read the manual for strptime and I also looked at many examples, but when I try to apply it to my code, I always encounter some problems.
I try to change the default format, with no success. Why? How can I change the format?

1.
init_day <- as.factor("2015-02-24-00-30")
strptime(init_day, format="%Y-%m-%d-%H-%M")
[1] "2015-02-24 00:30:00"
It works, but why also seconds are shown if in format seconds are not specified?

2.
init_day <- as.factor("2015-02-24-0-00")
strptime(init_day, format="%Y-%m-%d-%H-%M")
[1] "2015-02-24"
Again, the specified format is not applied. Why?

Thank you for your attention and your help
Stefano


________________________________

AVVISO IMPORTANTE: Questo messaggio di posta elettronica può contenere informazioni confidenziali, pertanto è destinato solo a persone autorizzate alla ricezione. I messaggi di posta elettronica per i client di Regione Marche possono contenere informazioni confidenziali e con privilegi legali. Se non si è il destinatario specificato, non leggere, copiare, inoltrare o archiviare questo messaggio. Se si è ricevuto questo messaggio per errore, inoltrarlo al mittente ed eliminarlo completamente dal sistema del proprio computer. Ai sensi dell’art. 6 della DGR n. 1394/2008 si segnala che, in caso di necessità ed urgenza, la risposta al presente messaggio di posta elettronica può essere visionata da persone estranee al destinatario.
IMPORTANT NOTICE: This e-mail message is intended to be received only by persons entitled to receive the confidential information it may contain. E-mail messages to clients of Regione Marche may contain information that is confidential and legally privileged. Please do not read, copy, forward, or store this message unless you are an intended recipient of it. If you have received this message in error, please forward it to the sender and delete it completely from your computer system.

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Re: Query about use of format in strptime

Jim Lemon-4
Hi Stefano,
As the help page says:

"The default for the format methods is "%Y-%m-%d %H:%M:%S" if any
element has a time component which is not midnight, and "%Y-%m-%d"
otherwise. This is because when the result is printed, it uses the
default format. If you want a specified output representation:

format(strptime(init_day, format="%Y-%m-%d-%H-%M"),"%Y-%M-%d %H:%M")
[1] "2015-30-24 00:30"

For the "midnight" case:

format(strptime(init_day, format="%Y-%m-%d-%H-%M"),"%Y-%m-%d %H:%M")
[1] "2015-02-24 00:00"

Jim


On Mon, Apr 11, 2016 at 5:22 PM, Stefano Sofia
<[hidden email]> wrote:

> Dear R-list users,
> I need to use strptime because I have to deal with date with hours and minutes.
> I read the manual for strptime and I also looked at many examples, but when I try to apply it to my code, I always encounter some problems.
> I try to change the default format, with no success. Why? How can I change the format?
>
> 1.
> init_day <- as.factor("2015-02-24-00-30")
> strptime(init_day, format="%Y-%m-%d-%H-%M")
> [1] "2015-02-24 00:30:00"
> It works, but why also seconds are shown if in format seconds are not specified?
>
> 2.
> init_day <- as.factor("2015-02-24-0-00")
> strptime(init_day, format="%Y-%m-%d-%H-%M")
> [1] "2015-02-24"
> Again, the specified format is not applied. Why?
>
> Thank you for your attention and your help
> Stefano
>
>
> ________________________________
>
> AVVISO IMPORTANTE: Questo messaggio di posta elettronica può contenere informazioni confidenziali, pertanto è destinato solo a persone autorizzate alla ricezione. I messaggi di posta elettronica per i client di Regione Marche possono contenere informazioni confidenziali e con privilegi legali. Se non si è il destinatario specificato, non leggere, copiare, inoltrare o archiviare questo messaggio. Se si è ricevuto questo messaggio per errore, inoltrarlo al mittente ed eliminarlo completamente dal sistema del proprio computer. Ai sensi dell’art. 6 della DGR n. 1394/2008 si segnala che, in caso di necessità ed urgenza, la risposta al presente messaggio di posta elettronica può essere visionata da persone estranee al destinatario.
> IMPORTANT NOTICE: This e-mail message is intended to be received only by persons entitled to receive the confidential information it may contain. E-mail messages to clients of Regione Marche may contain information that is confidential and legally privileged. Please do not read, copy, forward, or store this message unless you are an intended recipient of it. If you have received this message in error, please forward it to the sender and delete it completely from your computer system.
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> [hidden email] 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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Re: Query about use of format in strptime

Enrico Schumann-2
In reply to this post by Stefano Sofia
On Mon, 11 Apr 2016, Stefano Sofia <[hidden email]> writes:

> Dear R-list users,
> I need to use strptime because I have to deal with date with hours and minutes.
> I read the manual for strptime and I also looked at many examples, but when I try to apply it to my code, I always encounter some problems.
> I try to change the default format, with no success. Why? How can I change the format?
>
> 1.
> init_day <- as.factor("2015-02-24-00-30")
> strptime(init_day, format="%Y-%m-%d-%H-%M")
> [1] "2015-02-24 00:30:00"
> It works, but why also seconds are shown if in format seconds are not specified?
>
> 2.
> init_day <- as.factor("2015-02-24-0-00")
> strptime(init_day, format="%Y-%m-%d-%H-%M")
> [1] "2015-02-24"
> Again, the specified format is not applied. Why?
>
> Thank you for your attention and your help
> Stefano


strptime creates a POSIXlt object, and the specified format
tells it how to interpret the string you pass in. (Your
factor is converted to character by strptime.)

If you want to have the POSIXlt object printed in a
particular way, use ?strftime or ?format.

  > format(strptime(init_day, format="%Y-%m-%d-%H-%M"), "%Y-%m-%d-%H-%M")
  ## [1] "2015-02-24-00-00"


--
Enrico Schumann
Lucerne, Switzerland
http://enricoschumann.net

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Re: Query about use of format in strptime

Stefano Sofia
In reply to this post by Jim Lemon-4
Dear Jim and dear Enrico,
thank you for your replies.
Unfortunately your hints didn't solve my problem, and I am getting mad.
Can I show you my whole process? I will be as quick as possible.
I start from a data frame called Snow of the form

year month day hh mm hs
2007 11 19 0 0 0.00
2007 11 19 0 30 0.00
2007 11 19 1 0 0.00
2007 11 19 1 30 0.00
2007 11 19 2 0 0.00
2007 11 19 2 30 0.00
2007 11 19 3 0 0.00
2007 11 19 3 30 0.00
2007 11 19 4 0 0.00
2007 11 19 4 30 0.00
...

whth semi-hourly data.
I need to deal with date so I used strptime:

Snow$data_factor <- as.factor(paste(Snow$year, Snow$month, Snow$day, Snow$hh, Snow$mm, sep="-"))
Snow$data_strptime <- strptime(Snow$data_factor, format = "%Y-%m-%d-%H-%M")

It gives me

year month day hh mm hs  data_factor  data_strptime
1     2007    11  19  0  0  0  2007-11-19-0-0 2007-11-19 00:00:00
2     2007    11  19  0 30  0  2007-11-19-0-30  2007-11-19 00:30:00
3     2007    11  19  1  0  0  2007-11-19-1-0  2007-11-19 01:00:00
4     2007    11  19  1 30  0  2007-11-19-1-30  2007-11-19 01:30:00
5     2007    11  19  2  0  0  2007-11-19-2-0  2007-11-19 02:00:00
6     2007    11  19  2 30  0  2007-11-19-2-30  2007-11-19 02:30:00
7     2007    11  19  3  0  0  2007-11-19-3-0  2007-11-19 03:00:00
8     2007    11  19  3 30  0  2007-11-19-3-30  2007-11-19 03:30:00
9     2007    11  19  4  0  0  2007-11-19-4-0  2007-11-19 04:00:00
10   2007    11  19  4 30  0  2007-11-19-4-30  2007-11-19 04:30:00
...

The type of the column data_strptime is
$data_strptime
[1] "POSIXlt" "POSIXt"

Because of some days (or part of them) might be missing, given a time interval I want to create a new data frame with all time-steps and then merge the new data frame with the old one.
In order to create a new data frame with all time-steps, I thought to use

df_new <- data.frame(data_strptime=seq(init_day, fin_day, by="30 mins"))

and then

Snow_all <- merge(df_new, Snow, by=("data_strptime"), all.x=TRUE)

My problem is in dealing with init_day and fin_day, respectively for example "200711190000" and "200711210000".
I am not able to create a sequence of class "POSIXlt" "POSIXt", in order to merge the two data frames.

Could you please help me in this?
Thank you again for your attention
Stefano


________________________________________
Da: Jim Lemon [[hidden email]]
Inviato: lunedì 11 aprile 2016 9.47
A: Stefano Sofia
Cc: [hidden email]
Oggetto: Re: [R] Query about use of format in strptime

Hi Stefano,
As the help page says:

"The default for the format methods is "%Y-%m-%d %H:%M:%S" if any
element has a time component which is not midnight, and "%Y-%m-%d"
otherwise. This is because when the result is printed, it uses the
default format. If you want a specified output representation:

format(strptime(init_day, format="%Y-%m-%d-%H-%M"),"%Y-%M-%d %H:%M")
[1] "2015-30-24 00:30"

For the "midnight" case:

format(strptime(init_day, format="%Y-%m-%d-%H-%M"),"%Y-%m-%d %H:%M")
[1] "2015-02-24 00:00"

Jim


On Mon, Apr 11, 2016 at 5:22 PM, Stefano Sofia
<[hidden email]> wrote:

> Dear R-list users,
> I need to use strptime because I have to deal with date with hours and minutes.
> I read the manual for strptime and I also looked at many examples, but when I try to apply it to my code, I always encounter some problems.
> I try to change the default format, with no success. Why? How can I change the format?
>
> 1.
> init_day <- as.factor("2015-02-24-00-30")
> strptime(init_day, format="%Y-%m-%d-%H-%M")
> [1] "2015-02-24 00:30:00"
> It works, but why also seconds are shown if in format seconds are not specified?
>
> 2.
> init_day <- as.factor("2015-02-24-0-00")
> strptime(init_day, format="%Y-%m-%d-%H-%M")
> [1] "2015-02-24"
> Again, the specified format is not applied. Why?
>
> Thank you for your attention and your help
> Stefano
>
>
> ________________________________
>
> AVVISO IMPORTANTE: Questo messaggio di posta elettronica può contenere informazioni confidenziali, pertanto è destinato solo a persone autorizzate alla ricezione. I messaggi di posta elettronica per i client di Regione Marche possono contenere informazioni confidenziali e con privilegi legali. Se non si è il destinatario specificato, non leggere, copiare, inoltrare o archiviare questo messaggio. Se si è ricevuto questo messaggio per errore, inoltrarlo al mittente ed eliminarlo completamente dal sistema del proprio computer. Ai sensi dell’art. 6 della DGR n. 1394/2008 si segnala che, in caso di necessità ed urgenza, la risposta al presente messaggio di posta elettronica può essere visionata da persone estranee al destinatario.
> IMPORTANT NOTICE: This e-mail message is intended to be received only by persons entitled to receive the confidential information it may contain. E-mail messages to clients of Regione Marche may contain information that is confidential and legally privileged. Please do not read, copy, forward, or store this message unless you are an intended recipient of it. If you have received this message in error, please forward it to the sender and delete it completely from your computer system.
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> [hidden email] 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.

________________________________

AVVISO IMPORTANTE: Questo messaggio di posta elettronica può contenere informazioni confidenziali, pertanto è destinato solo a persone autorizzate alla ricezione. I messaggi di posta elettronica per i client di Regione Marche possono contenere informazioni confidenziali e con privilegi legali. Se non si è il destinatario specificato, non leggere, copiare, inoltrare o archiviare questo messaggio. Se si è ricevuto questo messaggio per errore, inoltrarlo al mittente ed eliminarlo completamente dal sistema del proprio computer. Ai sensi dell’art. 6 della DGR n. 1394/2008 si segnala che, in caso di necessità ed urgenza, la risposta al presente messaggio di posta elettronica può essere visionata da persone estranee al destinatario.
IMPORTANT NOTICE: This e-mail message is intended to be received only by persons entitled to receive the confidential information it may contain. E-mail messages to clients of Regione Marche may contain information that is confidential and legally privileged. Please do not read, copy, forward, or store this message unless you are an intended recipient of it. If you have received this message in error, please forward it to the sender and delete it completely from your computer system.

______________________________________________
[hidden email] mailing list -- To UNSUBSCRIBE and more, see
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Re: Query about use of format in strptime

David Winsemius

> On Apr 11, 2016, at 1:48 AM, Stefano Sofia <[hidden email]> wrote:
>
> Dear Jim and dear Enrico,
> thank you for your replies.
> Unfortunately your hints didn't solve my problem, and I am getting mad.
> Can I show you my whole process? I will be as quick as possible.
> I start from a data frame called Snow of the form
>
> year month day hh mm hs
> 2007 11 19 0 0 0.00
> 2007 11 19 0 30 0.00
> 2007 11 19 1 0 0.00
> 2007 11 19 1 30 0.00
> 2007 11 19 2 0 0.00
> 2007 11 19 2 30 0.00
> 2007 11 19 3 0 0.00
> 2007 11 19 3 30 0.00
> 2007 11 19 4 0 0.00
> 2007 11 19 4 30 0.00
> ...
>
> whth semi-hourly data.
> I need to deal with date so I used strptime:
>
> Snow$data_factor <- as.factor(paste(Snow$year, Snow$month, Snow$day, Snow$hh, Snow$mm, sep="-"))
> Snow$data_strptime <- strptime(Snow$data_factor, format = "%Y-%m-%d-%H-%M")
>
> It gives me
>
> year month day hh mm hs  data_factor  data_strptime
> 1     2007    11  19  0  0  0  2007-11-19-0-0 2007-11-19 00:00:00
> 2     2007    11  19  0 30  0  2007-11-19-0-30  2007-11-19 00:30:00
> 3     2007    11  19  1  0  0  2007-11-19-1-0  2007-11-19 01:00:00
> 4     2007    11  19  1 30  0  2007-11-19-1-30  2007-11-19 01:30:00
> 5     2007    11  19  2  0  0  2007-11-19-2-0  2007-11-19 02:00:00
> 6     2007    11  19  2 30  0  2007-11-19-2-30  2007-11-19 02:30:00
> 7     2007    11  19  3  0  0  2007-11-19-3-0  2007-11-19 03:00:00
> 8     2007    11  19  3 30  0  2007-11-19-3-30  2007-11-19 03:30:00
> 9     2007    11  19  4  0  0  2007-11-19-4-0  2007-11-19 04:00:00
> 10   2007    11  19  4 30  0  2007-11-19-4-30  2007-11-19 04:30:00
> ...
>
> The type of the column data_strptime is
> $data_strptime
> [1] "POSIXlt" "POSIXt"
>
> Because of some days (or part of them) might be missing, given a time interval I want to create a new data frame with all time-steps and then merge the new data frame with the old one.
> In order to create a new data frame with all time-steps, I thought to use
>
> df_new <- data.frame(data_strptime=seq(init_day, fin_day, by="30 mins"))
>
> and then
>
> Snow_all <- merge(df_new, Snow, by=("data_strptime"), all.x=TRUE)
>
> My problem is in dealing with  and , respectively for example "200711190000" and "200711210000".
> I am not able to create a sequence of class "POSIXlt" "POSIXt", in order to merge the two data frames.



First you asked about character values with dashes in them and now you want no dashes. Make up our mind:


init_day="200711190000"
 fin_day="200711210000".
df_new <- data.frame(data_strptime=seq(as.POSIXct(init_day, %Y%M%D%H%M"),
                                       as.POSIXct(fin_day, %Y%M%D%H%M"), by="30 mins"))

Do NOT use POSIXlt for dataframe columns.

--
David.


>
> Could you please help me in this?
> Thank you again for your attention
> Stefano
>
>
> ________________________________________
> Da: Jim Lemon [[hidden email]]
> Inviato: lunedì 11 aprile 2016 9.47
> A: Stefano Sofia
> Cc: [hidden email]
> Oggetto: Re: [R] Query about use of format in strptime
>
> Hi Stefano,
> As the help page says:
>
> "The default for the format methods is "%Y-%m-%d %H:%M:%S" if any
> element has a time component which is not midnight, and "%Y-%m-%d"
> otherwise. This is because when the result is printed, it uses the
> default format. If you want a specified output representation:
>
> format(strptime(init_day, format="%Y-%m-%d-%H-%M"),"%Y-%M-%d %H:%M")
> [1] "2015-30-24 00:30"
>
> For the "midnight" case:
>
> format(strptime(init_day, format="%Y-%m-%d-%H-%M"),"%Y-%m-%d %H:%M")
> [1] "2015-02-24 00:00"
>
> Jim
>
>
> On Mon, Apr 11, 2016 at 5:22 PM, Stefano Sofia
> <[hidden email]> wrote:
>> Dear R-list users,
>> I need to use strptime because I have to deal with date with hours and minutes.
>> I read the manual for strptime and I also looked at many examples, but when I try to apply it to my code, I always encounter some problems.
>> I try to change the default format, with no success. Why? How can I change the format?
>>
>> 1.
>> init_day <- as.factor("2015-02-24-00-30")
>> strptime(init_day, format="%Y-%m-%d-%H-%M")
>> [1] "2015-02-24 00:30:00"
>> It works, but why also seconds are shown if in format seconds are not specified?
>>
>> 2.
>> init_day <- as.factor("2015-02-24-0-00")
>> strptime(init_day, format="%Y-%m-%d-%H-%M")
>> [1] "2015-02-24"
>> Again, the specified format is not applied. Why?
>>
>> Thank you for your attention and your help
>> Stefano
>>
>>
>> ________________________________
>>
>> AVVISO IMPORTANTE: Questo messaggio di posta elettronica può contenere informazioni confidenziali, pertanto è destinato solo a persone autorizzate alla ricezione. I messaggi di posta elettronica per i client di Regione Marche possono contenere informazioni confidenziali e con privilegi legali. Se non si è il destinatario specificato, non leggere, copiare, inoltrare o archiviare questo messaggio. Se si è ricevuto questo messaggio per errore, inoltrarlo al mittente ed eliminarlo completamente dal sistema del proprio computer. Ai sensi dell’art. 6 della DGR n. 1394/2008 si segnala che, in caso di necessità ed urgenza, la risposta al presente messaggio di posta elettronica può essere visionata da persone estranee al destinatario.
>> IMPORTANT NOTICE: This e-mail message is intended to be received only by persons entitled to receive the confidential information it may contain. E-mail messages to clients of Regione Marche may contain information that is confidential and legally privileged. Please do not read, copy, forward, or store this message unless you are an intended recipient of it. If you have received this message in error, please forward it to the sender and delete it completely from your computer system.
>>
>>        [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> [hidden email] 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.
>
> ________________________________
>
> AVVISO IMPORTANTE: Questo messaggio di posta elettronica può contenere informazioni confidenziali, pertanto è destinato solo a persone autorizzate alla ricezione. I messaggi di posta elettronica per i client di Regione Marche possono contenere informazioni confidenziali e con privilegi legali. Se non si è il destinatario specificato, non leggere, copiare, inoltrare o archiviare questo messaggio. Se si è ricevuto questo messaggio per errore, inoltrarlo al mittente ed eliminarlo completamente dal sistema del proprio computer. Ai sensi dell’art. 6 della DGR n. 1394/2008 si segnala che, in caso di necessità ed urgenza, la risposta al presente messaggio di posta elettronica può essere visionata da persone estranee al destinatario.
> IMPORTANT NOTICE: This e-mail message is intended to be received only by persons entitled to receive the confidential information it may contain. E-mail messages to clients of Regione Marche may contain information that is confidential and legally privileged. Please do not read, copy, forward, or store this message unless you are an intended recipient of it. If you have received this message in error, please forward it to the sender and delete it completely from your computer system.
>
> ______________________________________________
> [hidden email] 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.

David Winsemius
Alameda, CA, USA

______________________________________________
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Re: Query about use of format in strptime

MacQueen, Don
In reply to this post by Stefano Sofia
First I added one row to your data, to illustrate a case with missing
times:

year month day hh mm hs
2007 11 19 0 0 0.00
2007 11 19 0 30 0.00
2007 11 19 1 0 0.00
2007 11 19 1 30 0.00
2007 11 19 2 0 0.00
2007 11 19 2 30 0.00
2007 11 19 3 0 0.00
2007 11 19 3 30 0.00
2007 11 19 4 0 0.00
2007 11 19 4 30 0.00
2007 11 19 6 30 0.00

(and I put it in a separate file named snowday.dat)

Then try this:

sd <- read.table('snowday.dat', sep=' ', head=TRUE)
sd$tm <- as.POSIXct( paste(sd$year, sd$month, sd$day, sd$hh, sd$mm,
sep='-'), format='%Y-%m-%d-%H-%M')
dft <- data.frame( tm=seq(min(sd$tm), max(sd$tm), by='30 min') )
sd <- merge(sd, dft, all=TRUE)



This appears to do what you are asking for (if I understand correctly).

> sd
                    tm year month day hh mm hs
1  2007-11-19 00:00:00 2007    11  19  0  0  0
2  2007-11-19 00:30:00 2007    11  19  0 30  0
3  2007-11-19 01:00:00 2007    11  19  1  0  0
4  2007-11-19 01:30:00 2007    11  19  1 30  0
5  2007-11-19 02:00:00 2007    11  19  2  0  0
6  2007-11-19 02:30:00 2007    11  19  2 30  0
7  2007-11-19 03:00:00 2007    11  19  3  0  0
8  2007-11-19 03:30:00 2007    11  19  3 30  0
9  2007-11-19 04:00:00 2007    11  19  4  0  0
10 2007-11-19 04:30:00 2007    11  19  4 30  0
11 2007-11-19 05:00:00   NA    NA  NA NA NA NA
12 2007-11-19 05:30:00   NA    NA  NA NA NA NA
13 2007-11-19 06:00:00   NA    NA  NA NA NA NA
14 2007-11-19 06:30:00 2007    11  19  6 30  0



Notes:
There is no need to use factor()
As David said, don't use POSIXlt. Use POSIXct instead.

--
Don MacQueen

Lawrence Livermore National Laboratory
7000 East Ave., L-627
Livermore, CA 94550
925-423-1062





On 4/11/16, 1:48 AM, "R-help on behalf of Stefano Sofia"
<[hidden email] on behalf of
[hidden email]> wrote:

>Dear Jim and dear Enrico,
>thank you for your replies.
>Unfortunately your hints didn't solve my problem, and I am getting mad.
>Can I show you my whole process? I will be as quick as possible.
>I start from a data frame called Snow of the form
>
>year month day hh mm hs
>2007 11 19 0 0 0.00
>2007 11 19 0 30 0.00
>2007 11 19 1 0 0.00
>2007 11 19 1 30 0.00
>2007 11 19 2 0 0.00
>2007 11 19 2 30 0.00
>2007 11 19 3 0 0.00
>2007 11 19 3 30 0.00
>2007 11 19 4 0 0.00
>2007 11 19 4 30 0.00
>...
>
>whth semi-hourly data.
>I need to deal with date so I used strptime:
>
>Snow$data_factor <- as.factor(paste(Snow$year, Snow$month, Snow$day,
>Snow$hh, Snow$mm, sep="-"))
>Snow$data_strptime <- strptime(Snow$data_factor, format =
>"%Y-%m-%d-%H-%M")
>
>It gives me
>
>year month day hh mm hs  data_factor  data_strptime
>1     2007    11  19  0  0  0  2007-11-19-0-0 2007-11-19 00:00:00
>2     2007    11  19  0 30  0  2007-11-19-0-30  2007-11-19 00:30:00
>3     2007    11  19  1  0  0  2007-11-19-1-0  2007-11-19 01:00:00
>4     2007    11  19  1 30  0  2007-11-19-1-30  2007-11-19 01:30:00
>5     2007    11  19  2  0  0  2007-11-19-2-0  2007-11-19 02:00:00
>6     2007    11  19  2 30  0  2007-11-19-2-30  2007-11-19 02:30:00
>7     2007    11  19  3  0  0  2007-11-19-3-0  2007-11-19 03:00:00
>8     2007    11  19  3 30  0  2007-11-19-3-30  2007-11-19 03:30:00
>9     2007    11  19  4  0  0  2007-11-19-4-0  2007-11-19 04:00:00
>10   2007    11  19  4 30  0  2007-11-19-4-30  2007-11-19 04:30:00
>...
>
>The type of the column data_strptime is
>$data_strptime
>[1] "POSIXlt" "POSIXt"
>
>Because of some days (or part of them) might be missing, given a time
>interval I want to create a new data frame with all time-steps and then
>merge the new data frame with the old one.
>In order to create a new data frame with all time-steps, I thought to use
>
>df_new <- data.frame(data_strptime=seq(init_day, fin_day, by="30 mins"))
>
>and then
>
>Snow_all <- merge(df_new, Snow, by=("data_strptime"), all.x=TRUE)
>
>My problem is in dealing with init_day and fin_day, respectively for
>example "200711190000" and "200711210000".
>I am not able to create a sequence of class "POSIXlt" "POSIXt", in order
>to merge the two data frames.
>
>Could you please help me in this?
>Thank you again for your attention
>Stefano
>
>
>________________________________________
>Da: Jim Lemon [[hidden email]]
>Inviato: lunedì 11 aprile 2016 9.47
>A: Stefano Sofia
>Cc: [hidden email]
>Oggetto: Re: [R] Query about use of format in strptime
>
>Hi Stefano,
>As the help page says:
>
>"The default for the format methods is "%Y-%m-%d %H:%M:%S" if any
>element has a time component which is not midnight, and "%Y-%m-%d"
>otherwise. This is because when the result is printed, it uses the
>default format. If you want a specified output representation:
>
>format(strptime(init_day, format="%Y-%m-%d-%H-%M"),"%Y-%M-%d %H:%M")
>[1] "2015-30-24 00:30"
>
>For the "midnight" case:
>
>format(strptime(init_day, format="%Y-%m-%d-%H-%M"),"%Y-%m-%d %H:%M")
>[1] "2015-02-24 00:00"
>
>Jim
>
>
>On Mon, Apr 11, 2016 at 5:22 PM, Stefano Sofia
><[hidden email]> wrote:
>> Dear R-list users,
>> I need to use strptime because I have to deal with date with hours and
>>minutes.
>> I read the manual for strptime and I also looked at many examples, but
>>when I try to apply it to my code, I always encounter some problems.
>> I try to change the default format, with no success. Why? How can I
>>change the format?
>>
>> 1.
>> init_day <- as.factor("2015-02-24-00-30")
>> strptime(init_day, format="%Y-%m-%d-%H-%M")
>> [1] "2015-02-24 00:30:00"
>> It works, but why also seconds are shown if in format seconds are not
>>specified?
>>
>> 2.
>> init_day <- as.factor("2015-02-24-0-00")
>> strptime(init_day, format="%Y-%m-%d-%H-%M")
>> [1] "2015-02-24"
>> Again, the specified format is not applied. Why?
>>
>> Thank you for your attention and your help
>> Stefano
>>
>>
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>
>________________________________
>
>AVVISO IMPORTANTE: Questo messaggio di posta elettronica può contenere
>informazioni confidenziali, pertanto è destinato solo a persone
>autorizzate alla ricezione. I messaggi di posta elettronica per i client
>di Regione Marche possono contenere informazioni confidenziali e con
>privilegi legali. Se non si è il destinatario specificato, non leggere,
>copiare, inoltrare o archiviare questo messaggio. Se si è ricevuto questo
>messaggio per errore, inoltrarlo al mittente ed eliminarlo completamente
>dal sistema del proprio computer. Ai sensi dell¹art. 6 della DGR n.
>1394/2008 si segnala che, in caso di necessità ed urgenza, la risposta al
>presente messaggio di posta elettronica può essere visionata da persone
>estranee al destinatario.
>IMPORTANT NOTICE: This e-mail message is intended to be received only by
>persons entitled to receive the confidential information it may contain.
>E-mail messages to clients of Regione Marche may contain information that
>is confidential and legally privileged. Please do not read, copy,
>forward, or store this message unless you are an intended recipient of
>it. If you have received this message in error, please forward it to the
>sender and delete it completely from your computer system.
>
>______________________________________________
>[hidden email] 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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