[R] Date Time in R

Shivi Bhatia shivipmp82 at gmail.com
Tue Jul 26 18:59:20 CEST 2016


These are some of the codes will i have
eir$date<- as.Date(eir$date, "%d-%m-%Y")
class(eir$date)
eir$week<- (eir$date)
eir$week<- weekdays(as.Date(eir$week))
eir$week<- as.factor(eir$week)

On Tue, Jul 26, 2016 at 10:24 PM, Shivi Bhatia <shivipmp82 at gmail.com> wrote:

> Hi Bill,
>
> I have mentioned the transformation all on the email above.
>
> Regards, Shivi
>
> On Tue, Jul 26, 2016 at 10:19 PM, William Dunlap <wdunlap at tibco.com>
> wrote:
>
>> Can you show us what transformations you tried when
>> you saw the column called 'date' was a factor?
>>
>> Bill Dunlap
>> TIBCO Software
>> wdunlap tibco.com
>>
>> On Tue, Jul 26, 2016 at 9:33 AM, Shivi Bhatia <shivipmp82 at gmail.com>
>> wrote:
>>
>>> Thanks Tom for the recommendation. This is now working.
>>>
>>> Apologies if this sounds like a juvenile but i am not very good with
>>> dates
>>> in R. What i initially did when i saw date as factor and then tried
>>> converting with lot many transformation that is where it went bad.
>>>
>>> But thanks to all this is really what i wanted.
>>>
>>> On Tue, Jul 26, 2016 at 9:58 PM, Tom Wright <tom at maladmin.com> wrote:
>>>
>>> > So this looks correct so far.
>>> >
>>> >
>>> >
>>> > # convert strings (or factors) to a date object
>>> >
>>> > a1$date <- as.Date(a1$date, “%m-%d-%y”)
>>> >
>>> >
>>> >
>>> > # Note the date object is now displayed in the format %Y-%m-%d by
>>> default
>>> >
>>> > # so no need for the mdy() or ymd() function
>>> >
>>> >
>>> >
>>> > # extract the weekdays as number
>>> >
>>> > weekdays <- wday(a1$date)
>>> >
>>> >
>>> >
>>> > # note can’t have spaces in variable names
>>> >
>>> > week_names <- wday(a1$date, label=TRUE)
>>> >
>>> >
>>> >
>>> >
>>> >
>>> > *From:* Shivi Bhatia [mailto:shivipmp82 at gmail.com]
>>> > *Sent:* July 26, 2016 12:16 PM
>>> > *To:* Tom Wright <tom at maladmin.com>
>>> > *Cc:* David L Carlson <dcarlson at tamu.edu>; r-help <
>>> r-help at r-project.org>
>>>
>>> >
>>> > *Subject:* Re: [R] Date Time in R
>>> >
>>> >
>>> >
>>> > Hello Tom,
>>> >
>>> >
>>> >
>>> > Please find the details: (i have changed name from eir to a1, rest all
>>> is
>>> > same)
>>> >
>>> >
>>> >
>>> > str(a1$date)
>>> >
>>> >  Factor w/ 32 levels "05-30-16","05-31-16",..: 1 1 1
>>> >
>>> >
>>> >
>>> > head(a1$date)
>>> >
>>> > 05-30-16 05-30-16 05-30-16 05-30-16 05-30-16 05-30-16
>>> >
>>> > 32 Levels: 05-30-16 05-31-16 06-01-16 06-02-16 06-03-16 06-04-16
>>> 06-05-16
>>> > 06-06-16 06-07-16 06-08-16
>>> >
>>> >
>>> >
>>> > Thanks again!!!
>>> >
>>> >
>>> >
>>> > On Tue, Jul 26, 2016 at 9:38 PM, Tom Wright <tom at maladmin.com> wrote:
>>> >
>>> > Hi again Shiva,
>>> > I think what we need to see is the output from:
>>> >
>>> > str(eid$date)
>>> >
>>> > and perhaps
>>> > head(eid$date)
>>> >
>>> > If you can send this information before doing any processing on the
>>> date
>>> > (i.e. before the as.Date() function) we may be able to help.
>>> >
>>> >
>>> >
>>> > -----Original Message-----
>>> > From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Shivi
>>> > Bhatia
>>> > Sent: July 26, 2016 11:46 AM
>>> > To: David L Carlson <dcarlson at tamu.edu>
>>> > Cc: r-help <r-help at r-project.org>
>>> > Subject: Re: [R] Date Time in R
>>> >
>>> > Hi David please see the code and some reproducible data:
>>> > eir$date<- as.Date(eir$date,format = "%m-%d-%y")  then i had used the
>>> > lubridate library to help with the dates:
>>> > install.packages("lubridate")
>>> > library(lubridate)
>>> > eir$date <- mdy(eir$date)
>>> > weekdays <- wdy(eir$date)
>>> > week names <- wdy(eir$date, label = TRUE)
>>> >
>>> > This the output from the file:
>>> >
>>> > structure(list(date = structure(c(NA_real_, NA_real_, NA_real_), class
>>> =
>>> > "Date"),
>>> >
>>> > month = structure(c(2L, 2L, 2L), .Label = c("Jun","May"), class =
>>> > "factor"),
>>> >
>>> > day = c(30L, 30L, 30L),
>>> >
>>> > weekday = structure(c(2L,2L, 2L), .Label = c("Fri", "Mon", "Sat",
>>> "Sun",
>>> > "Thu", "Tue","Wed"), class = "factor"),
>>> >
>>> > survey_rating = c(3L, 2L, 3L), query_status = c("Yes", "Don't
>>> know","No"),
>>> >
>>> >  a = c("05-30-16", "05-30-16", "05-30-16")), .Names = c("date","month",
>>> > "day", "weekday", "survey_rating"), row.names = c(NA, 3L), class =
>>> > "data.frame")
>>> >
>>> > There are several other variables that i have removed which are not
>>> > relevant
>>> > in this context.
>>> >
>>> > On Tue, Jul 26, 2016 at 8:55 PM, David L Carlson <dcarlson at tamu.edu>
>>> > wrote:
>>> >
>>> > > Show us the output, don’t just tell us what you are seeing. If the
>>> > > dates are correct in the csv file, show us the structure of the data
>>> > > frame you created with read.csv() and show the command(s) you used to
>>> > > convert the character data to date format. The solution is likely to
>>> > > be simple if you will cut/paste the R console and not just describe
>>> what
>>> > > is happening.
>>> > >
>>> > >
>>> > >
>>> > > David C
>>> > >
>>> > >
>>> > >
>>> >
>>> > > *From:* Shivi Bhatia [mailto:shivipmp82 at gmail.com]
>>> > > *Sent:* Tuesday, July 26, 2016 10:08 AM
>>> > > *To:* David L Carlson
>>> > >
>>> > > *Subject:* Re: [R] Date Time in R
>>> >
>>> > >
>>> > >
>>> > >
>>> > > Hi David,
>>> > >
>>> > > This gives the results accurately. The first line shows all the
>>> > > variable names and the rest shows all values stored for each of the
>>> > > variable. Here date is appearing as correct.
>>> > >
>>> > >
>>> > >
>>> > > Thanks, Shivi
>>> > >
>>> > >
>>> > >
>>> > > On Tue, Jul 26, 2016 at 7:39 PM, David L Carlson <dcarlson at tamu.edu>
>>> > > wrote:
>>> > >
>>> > > What does this produce?
>>> > >
>>> > > > readLines("YourCSVfilename.csv", n=5)
>>> > >
>>> > > If the data are in Excel, the date format used in .csv files is not
>>> > > always in the same as the format used when viewing dates in the
>>> > > spreadsheet.
>>> > >
>>> > > -------------------------------------
>>> > > David L Carlson
>>> > > Department of Anthropology
>>> > > Texas A&M University
>>> > > College Station, TX 77840-4352
>>> > >
>>> > >
>>> > >
>>> > > -----Original Message-----
>>> > > From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of
>>> Shivi
>>> > > Bhatia
>>> > > Sent: Tuesday, July 26, 2016 7:42 AM
>>> > > To: Marc Schwartz
>>> > > Cc: R-help
>>> > > Subject: Re: [R] Date Time in R
>>> > >
>>> > > Thanks Marc for the help. this really helps.
>>> > > I think there is some issue with the data saved in csv format for
>>> this
>>> > > variable as when i checked:
>>> > > str(eir$date)- this results in :-
>>> > > Date[1:5327], format: NA NA NA NA NA.
>>> > >
>>> > > Thanks again.
>>> > >
>>> > > On Tue, Jul 26, 2016 at 5:58 PM, Marc Schwartz <marc_schwartz at me.com
>>> >
>>> > > wrote:
>>> > >
>>> > > > Hi,
>>> > > >
>>> > > > That eir$date might be a factor is irrelevant. There is an
>>> as.Date()
>>> > > > method for factors, which does the factor to character coercion
>>> > > internally
>>> > > > and then calls as.Date.character() on the result.
>>> > > >
>>> > > > Using the example data below:
>>> > > >
>>> > > > eir <- data.frame(date = c("05-30-16", "05-30-16", "05-30-16",
>>> > > >                            "05-30-16", "05-30-16", "05-30-16"))
>>> > > >
>>> > > > > str(eir)
>>> > > > 'data.frame':   6 obs. of  1 variable:
>>> > > >  $ date: Factor w/ 1 level "05-30-16": 1 1 1 1 1 1
>>> > > >
>>> > > > > eir
>>> > > >       date
>>> > > > 1 05-30-16
>>> > > > 2 05-30-16
>>> > > > 3 05-30-16
>>> > > > 4 05-30-16
>>> > > > 5 05-30-16
>>> > > > 6 05-30-16
>>> > > >
>>> > > > eir$date <- as.Date(eir$date, format = "%m-%d-%y")
>>> > > >
>>> > > > > str(eir)
>>> > > > 'data.frame':   6 obs. of  1 variable:
>>> > > >  $ date: Date, format: "2016-05-30" ...
>>> > > >
>>> > > > > eir
>>> > > >         date
>>> > > > 1 2016-05-30
>>> > > > 2 2016-05-30
>>> > > > 3 2016-05-30
>>> > > > 4 2016-05-30
>>> > > > 5 2016-05-30
>>> > > > 6 2016-05-30
>>> > > >
>>> > > > eir$days <- weekdays(eir$date)
>>> > > >
>>> > > > > str(eir)
>>> > > > 'data.frame':   6 obs. of  2 variables:
>>> > > >  $ date: Date, format: "2016-05-30" ...
>>> > > >  $ days: chr  "Monday" "Monday" "Monday" "Monday" ...
>>> > > >
>>> > > > > eir
>>> > > >         date   days
>>> > > > 1 2016-05-30 Monday
>>> > > > 2 2016-05-30 Monday
>>> > > > 3 2016-05-30 Monday
>>> > > > 4 2016-05-30 Monday
>>> > > > 5 2016-05-30 Monday
>>> > > > 6 2016-05-30 Monday
>>> > > >
>>> > > >
>>> > > > I would check to be sure that you do not have any typos in your
>>> code.
>>> > > >
>>> > > > Regards,
>>> > > >
>>> > > > Marc Schwartz
>>> > > >
>>> > > >
>>> > > > > On Jul 26, 2016, at 6:58 AM, Shivi Bhatia <shivipmp82 at gmail.com>
>>> > > wrote:
>>> > > > >
>>> > > > > Hello Again,
>>> > > > >
>>> > > > > While i tried your solution as you suggested above it seems to be
>>> > > > working.
>>> > > > > Here is the output
>>> > > > > temp<- dput(head(eir$date))
>>> > > > > c("05-30-16", "05-30-16", "05-30-16", "05-30-16", "05-30-16",
>>> > > "05-30-16")
>>> > > > > however it still shows class(eir$date) as character and hence i
>>> > > > > cannot
>>> > > > find
>>> > > > > weekdays from this variable.
>>> > > > >
>>> > > > > Sorry but i still dont understand in totality how R reads dates
>>> > > > > even
>>> > > > though
>>> > > > > have tried enough.
>>> > > > >
>>> > > > > Regards, Shivi
>>> > > > >
>>> > > > >
>>> > > > > On Tue, Jul 26, 2016 at 5:12 PM, Shivi Bhatia
>>> > > > > <shivipmp82 at gmail.com>
>>> > > > wrote:
>>> > > > >
>>> > > > >> Thanks Duncan for the quick response. I will check again as you
>>> > > > suggested.
>>> > > > >> If that doesn't work i will share a reproducible example.
>>> > > > >>
>>> > > > >> Thanks again!!!!
>>> > > > >>
>>> > > > >> On Tue, Jul 26, 2016 at 4:43 PM, Duncan Murdoch <
>>> > > > murdoch.duncan at gmail.com>
>>> > > > >> wrote:
>>> > > > >>
>>> > > > >>> On 26/07/2016 7:05 AM, Shivi Bhatia wrote:
>>> > > > >>>
>>> > > > >>>> Hi Team,
>>> > > > >>>>
>>> > > > >>>> This scenario may have come across a number of times however i
>>> > > checked
>>> > > > >>>> nabble & SO and couldn't find a solution hence request
>>> assistance.
>>> > > > >>>>
>>> > > > >>>> I have a date variable in my data-set eir. The class of this
>>> > > > >>>> var was character while i had read the file in r studio.
>>> > > > >>>> Example of date -
>>> > > > >>>> 05-30-16
>>> > > > >>>>
>>> > > > >>>> To change this i have used eir$date<- as.Date(eir$date,
>>> > > > >>>> "%m-%d-%y").
>>> > > > This
>>> > > > >>>> converts it to a date variable. However when i check few obs
>>> > > > >>>> with head(eir$date) all the results are <NA>.
>>> > > > >>>>
>>> > > > >>>
>>> > > > >>> I think you don't have character data like that, because I see
>>> > > > >>>
>>> > > > >>>> as.Date("05-30-16", "%m-%d-%y")
>>> > > > >>> [1] "2016-05-30"
>>> > > > >>>
>>> > > > >>> I'd guess eir$date is really a factor, because character data
>>> is
>>> > > > >>> frequently changed to factor automatically.  If that's the
>>> case,
>>> > > > >>> this should work for the conversion:
>>> > > > >>>
>>> > > > >>> as.Date(as.character(eir$date), "%m-%d-%y")
>>> > > > >>>
>>> > > > >>> If that doesn't work, you'll need to post something
>>> reproducible.
>>> > > > >>>
>>> > > > >>> Duncan Murdoch
>>> > > > >>>
>>> > > > >>> I also need to create weekdays from this date variable but
>>> until
>>> > > > >>> i
>>> > > get
>>> > > > >>>> this
>>> > > > >>>> resolved i cant find a weekday. For weekday i have used:
>>> > > > >>>> eir$week<- (eir$date)
>>> > > > >>>> eir$week<- weekdays(as.Date(eir$week))
>>> > > > >>>> class(eir$week)
>>> > > > >>>> eir$week<- as.factor(eir$week)
>>> > > > >>>> head(eir$week)
>>> > > > >>>>
>>> > > > >>>> Head of this eir$week results again as expected in <NA> but
>>> > > > >>>> shows
>>> > > > Levels:
>>> > > > >>>> Friday Monday Saturday Sunday Thursday Tuesday Wednesday
>>> > > > >>>>
>>> > > > >>>> Not sure what i should do here. Kindly suggest.
>>> > > >
>>> > > >
>>> > >
>>> > >         [[alternative HTML version deleted]]
>>> > >
>>> > > ______________________________________________
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>>> > > https://stat.ethz.ch/mailman/listinfo/r-help
>>> >
>>> > > <
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>>> > >
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>>> > >
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>>> >
>>> > > and provide commented, minimal, self-contained, reproducible code.
>>> > >
>>> > >
>>> > >
>>> >
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>>> >
>>> > ______________________________________________
>>> > 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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>>> >
>>> >
>>>
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>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>>> https://stat.ethz.ch/mailman/listinfo/r-help
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>>
>>
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