[R] Date Time in R
Shivi Bhatia
shivipmp82 at gmail.com
Tue Jul 26 17:45:46 CEST 2016
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.
> >
> >
>
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