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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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 <stefano.sofia at regione.marche.it> 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 pu? contenere informazioni confidenziali, pertanto ? 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 ? il destinatario specificato, non leggere, copiare, inoltrare o archiviare questo messaggio. Se si ? 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 necessit? ed urgenza, la risposta al presente messaggio di posta elettronica pu? 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]] > > ______________________________________________ > 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.
On Mon, 11 Apr 2016, Stefano Sofia <stefano.sofia at regione.marche.it> 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 > Stefanostrptime 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
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 [drjimlemon at gmail.com]
Inviato: luned? 11 aprile 2016 9.47
A: Stefano Sofia
Cc: r-help at r-project.org
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
<stefano.sofia at regione.marche.it> 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 pu? contenere
informazioni confidenziali, pertanto ? 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 ?
il destinatario specificato, non leggere, copiare, inoltrare o archiviare questo
messaggio. Se si ? 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 necessit? ed urgenza, la
risposta al presente messaggio di posta elettronica pu? 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]]
>
> ______________________________________________
> 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.
________________________________
AVVISO IMPORTANTE: Questo messaggio di posta elettronica pu? contenere
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ed eliminarlo completamente dal sistema del proprio computer. Ai sensi dell?art.
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risposta al presente messaggio di posta elettronica pu? essere visionata da
persone estranee al destinatario.
IMPORTANT NOTICE: This e-mail message is intended to be received only by persons
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to clients of Regione Marche may contain information that is confidential and
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