[R] as.Date

[David Winsemius]

> On Apr 18, 2016, at 10:44 AM, Ogbos Okike <giftedlife2014 at gmail.com> wrote:
> 
> Dear ALL,
> Thank you so much for your contributions.
> I have made some progress. Below is a simple script I gleaned from
> your kind responses:
> Sys.setenv(TZ="Etc/GMT")
> dates <- c("02/27/92", "02/27/92", "01/14/92", "02/28/92", "02/01/92")
>     times <- c("23:0:0", "22:0:0", "01:00:00", "18:0:0", "16:0:0")
>     x <- paste(dates, times)
>     aa<-strptime(x, "%m/%d/%y %H:%M:%S")
> bb<-1:5
> plot(aa, bb)
> 
> I tried plotting my result and I got what I am looking for. I think I
> am almost there.
> 
> I am, however, stuck here. My data is a large file and the form
> differs a little from the example I used. The quotation marks in both
> date and time is my headache now. Such inverted commas are not in my
> data. I can with awk transform my data to get exactly something like
> dd/mm/yy. But I wont know how to make the data appear in quotation
> mark in R.

There are not any quotation marks in an R object that is displayed as "02/27/92". The quotation marks are just added by the print function to make it clear to the user that it is a character value. 

If you read such values in with read.table they would automatically be interpreted as character values and then converted to factor class (which you do not want). Read up on the use in the read.* functions for colClasses and stringsAsFactors to safely input character values.
-- 
David.

> I will once more be glad for any more help.
> Ogbos
> 
> PS: I am still afraid of this forum. Please direct me to the right
> forum if this is not ok. Thanks again.
> 
> 
> On 4/18/16, peter dalgaard <pdalgd at gmail.com> wrote:
>> The most important thing is that Date objects by definition do not include
>> time of day. You want to look at ISOdatetime() and as.POSIXct() instead. And
>> beware daylight savings time issues.
>> 
>> -pd
>> 
>> On 18 Apr 2016, at 15:09 , Ogbos Okike <giftedlife2014 at gmail.com> wrote:
>> 
>>> Dear All,
>>> 
>>> I have a data set containing year, month, day and counts as shown below:
>>> data <- read.table("data.txt", col.names = c("year", "month", "day",
>>> "counts"))
>>> Using the formula below, I converted the data to as date and plotted.
>>> 
>>> new.century <- data$year < 70
>>> 
>>> data$year <- ifelse(new.century, data$year + 2000, data$year + 1900)
>>> 
>>> data$date <- as.Date(ISOdate(data$year, data$month, data$day))
>>> 
>>> The form of the data is:
>>> 16 1 19 9078
>>> 16 1 20 9060
>>> 16 1 21 9090
>>> 16 1 22 9080
>>> 16 1 23 9121
>>> 16 1 24 9199
>>> 16 1 25 9289
>>> 16 1 26 9285
>>> 16 1 27 9245
>>> 16 1 28 9223
>>> 16 1 29 9298
>>> 16 1 30 9327
>>> 16 1 31 9365
>>> 
>>> Now, I wish to include time (hour) in my data. The new data is of the
>>> form:
>>> 05 01 06 14    3849
>>> 05 01 06 15    3845
>>> 05 01 06 16    3836
>>> 05 01 06 17    3847
>>> 05 01 06 18    3850
>>> 05 01 06 19    3872
>>> 05 01 06 20    3849
>>> 05 01 06 21    3860
>>> 05 01 06 22    3868
>>> 05 01 06 23    3853
>>> 05 01 07 00    3839
>>> 05 01 07 01    3842
>>> 05 01 07 02    3843
>>> 05 01 07 03    3865
>>> 05 01 07 04    3879
>>> 05 01 07 05    3876
>>> 05 01 07 06    3867
>>> 05 01 07 07    3887
>>> 
>>> I now read the data as:
>>> data <- read.table("data.txt", col.names = c("year", "month", "day",
>>> "counts", "hour")) and also included hour in data$date <-
>>> as.Date(ISOdate(data$year, data$month, data$day))
>>> i.e data$date <- as.Date(ISOdate(data$year, data$month, data$day,
>>> data$hour)).
>>> 
>>> However, these did not work.
>>> 
>>> Can you please assist be on how to get this date and time in the right
>>> format. The right format I got without hour looks like : 2005-12-29"
>>> "2005-12-29" "2005-12-29" "2005-12-29" "2005-12-29"
>>> [8696] "2005-12-29" "2005-12-29" "2005-12-29" "2005-12-29" "2005-12-29"
>>> [8701] "2005-12-29" "2005-12-29" "2005-12-29" "2005-12-29" "2005-12-29"
>>> [8706] "2005-12-29" "2005-12-29" "2005-12-29" "2005-12-29" "2005-12-29"
>>> 
>>> I used this in my plot. Please I want this format to include hour.
>>> 
>>> Many thanks for your help. I am just a newbe. I am not sure if this
>>> forum is the right one. After registration, I tried to post to Nabble
>>> forum where I registered but could not succeed.
>>> 
>>> If there is a mistake, please help/direct me to the right forum.
>>> 
>>> Best regards
>>> Ogbos
>>> 
>>> ______________________________________________
>>> 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.
>> 
>> --
>> Peter Dalgaard, Professor,
>> Center for Statistics, Copenhagen Business School
>> Solbjerg Plads 3, 2000 Frederiksberg, Denmark
>> Phone: (+45)38153501
>> Office: A 4.23
>> Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com
>> 
>> 
> 
> ______________________________________________
> 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.

David Winsemius
Alameda, CA, USA