[R] Date Time in R

Shivi Bhatia shivipmp82 at gmail.com
Tue Jul 26 21:59:32 CEST 2016 

Thank you for all your tips. Will keep these checked.

Have a great day

On Wed, Jul 27, 2016 at 1:26 AM, William Dunlap <wdunlap at tibco.com> wrote:

> Your original mail said
>    Example of date - 05-30-16
>
>    To change this i have used eir$date<- as.Date(eir$date, "%m-%d-%y")
>
> but by showing us the actual code I see you reversed the m and d and
> capitalized the Y in your first attempt, causing NA's since your data was
> not in that format.
>
> The big mistake was overwriting the raw data with this mistakenly
> processed data so subsequent attempts at processing it failed.
>
> I recommend never overwriting the raw data - read the data into a
> data.frame called, say, 'raw' and make a new data.frame called, say,
> 'cleaned' with all the transformations based on the raw data.  Iterate the
> cleaning step until you have it right but don't alter the raw data.  Use
> functions like head(), str(), plot(), and summary() to see if things look
> basically ok.   The transform() function may help with that.  E.g.,
>
>     raw <- read.table(text="date\n05-30-16\n06-01-16\n06-27-16",
> header=TRUE)
>     str(raw)
>     #'data.frame':   3 obs. of  1 variable:
>     #$ date: Factor w/ 3 levels "05-30-16","06-01-16",..: 1 2 3
>     cleaned <- transform(raw, date=as.Date(date, format="%d-%m-%Y"))
>     head(cleaned)
>     #        date
>     #1       <NA>
>     #2 0016-01-06
>     #3       <NA>
>     cleaned <- transform(raw, date=as.Date(date, format="%d-%m-%y"))
>     head(cleaned)
>     #        date
>     #1       <NA>
>     #2 2016-01-06
>     #3       <NA>
>     cleaned <- transform(raw, date=as.Date(date, format="%m-%d-%y"))
>     head(cleaned)
>     #        date
>     #1 2016-05-30
>     #2 2016-06-01
>     #3 2016-06-27
> That last one looks ok, so move on to your next tranformation step.
>
>
>
>
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
>
> On Tue, Jul 26, 2016 at 9:59 AM, Shivi Bhatia <shivipmp82 at gmail.com>
> wrote:
>
>> 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]]
>>>>> > >
>>>>> > > ______________________________________________
>>>>> > > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>>>>> > > https://stat.ethz.ch/mailman/listinfo/r-help
>>>>> >
>>>>> > > <
>>>>> https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_mai
>>>>> > >
>>>>> lman_listinfo_r-2Dhelp&d=CwMFaQ&c=ODFT-G5SujMiGrKuoJJjVg&r=veMGHMCNZSh
>>>>> > >
>>>>> ld-KX-bIj4jRE_tP9ojUvB_Lqp0ieSdk&m=s9RjgM0-LqObg32B_ODUoHMjaBJSYFn0ccx
>>>>> > > orF0VRaQ&s=-2AvIVGKBvHIg4b3KBUCarOh98Mq95XbBM6rQR5o_Qw&e=>
>>>>> > > PLEASE do read the posting guide
>>>>> > > http://www.R-project.org/posting-guide.html
>>>>> > > <
>>>>> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.R-2Dproject.o
>>>>> > >
>>>>> rg_posting-2Dguide.html&d=CwMFaQ&c=ODFT-G5SujMiGrKuoJJjVg&r=veMGHMCNZS
>>>>> > >
>>>>> hld-KX-bIj4jRE_tP9ojUvB_Lqp0ieSdk&m=s9RjgM0-LqObg32B_ODUoHMjaBJSYFn0cc
>>>>> > > xorF0VRaQ&s=Ldb33UyU9KMUXEsxxzwItyCFjZInukICij2jo66xaKg&e=>
>>>>> >
>>>>> > > and provide commented, minimal, self-contained, reproducible code.
>>>>> > >
>>>>> > >
>>>>> > >
>>>>> >
>>>>> >         [[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.
>>>>> >
>>>>> >
>>>>> >
>>>>>
>>>>>         [[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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