Skip to content

as.Date

6 messages · Peter Dalgaard, PIKAL Petr, Jeff Newmiller +2 more

Ogbos Okike
# 
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
Peter Dalgaard
# 
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:

            

      
      
      
    

        

      
      
    

        

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      PIKAL Petr
    

    

      
      #
    

  


  

      
Hi

AFAIK as.Date does not accept hours. Although it is not explicitly written in help page, the name as.Date seems to me clear enough that it works only with dates.

If you want to use hours, minutes ... you should use strptime for converting your values to valid date_time object.

And you should also use ISOdatetime conversion function to use hours etc. in your commands.

Cheers
Petr

            

      
      
      
    

        

      
      
    

        
________________________________
Tento e-mail a jak?koliv k n?mu p?ipojen? dokumenty jsou d?v?rn? a jsou ur?eny pouze jeho adres?t?m.
Jestli?e jste obdr?el(a) tento e-mail omylem, informujte laskav? neprodlen? jeho odes?latele. Obsah tohoto emailu i s p??lohami a jeho kopie vyma?te ze sv?ho syst?mu.
Nejste-li zam??len?m adres?tem tohoto emailu, nejste opr?vn?ni tento email jakkoliv u??vat, roz?i?ovat, kop?rovat ?i zve?ej?ovat.
Odes?latel e-mailu neodpov?d? za eventu?ln? ?kodu zp?sobenou modifikacemi ?i zpo?d?n?m p?enosu e-mailu.

V p??pad?, ?e je tento e-mail sou??st? obchodn?ho jedn?n?:
- vyhrazuje si odes?latel pr?vo ukon?it kdykoliv jedn?n? o uzav?en? smlouvy, a to z jak?hokoliv d?vodu i bez uveden? d?vodu.
- a obsahuje-li nab?dku, je adres?t opr?vn?n nab?dku bezodkladn? p?ijmout; Odes?latel tohoto e-mailu (nab?dky) vylu?uje p?ijet? nab?dky ze strany p??jemce s dodatkem ?i odchylkou.
- trv? odes?latel na tom, ?e p??slu?n? smlouva je uzav?ena teprve v?slovn?m dosa?en?m shody na v?ech jej?ch n?le?itostech.
- odes?latel tohoto emailu informuje, ?e nen? opr?vn?n uzav?rat za spole?nost ??dn? smlouvy s v?jimkou p??pad?, kdy k tomu byl p?semn? zmocn?n nebo p?semn? pov??en a takov? pov??en? nebo pln? moc byly adres?tovi tohoto emailu p??padn? osob?, kterou adres?t zastupuje, p?edlo?eny nebo jejich existence je adres?tovi ?i osob? j?m zastoupen? zn?m?.

This e-mail and any documents attached to it may be confidential and are intended only for its intended recipients.
If you received this e-mail by mistake, please immediately inform its sender. Delete the contents of this e-mail with all attachments and its copies from your system.
If you are not the intended recipient of this e-mail, you are not authorized to use, disseminate, copy or disclose this e-mail in any manner.
The sender of this e-mail shall not be liable for any possible damage caused by modifications of the e-mail or by delay with transfer of the email.

In case that this e-mail forms part of business dealings:
- the sender reserves the right to end negotiations about entering into a contract in any time, for any reason, and without stating any reasoning.
- if the e-mail contains an offer, the recipient is entitled to immediately accept such offer; The sender of this e-mail (offer) excludes any acceptance of the offer on the part of the recipient containing any amendment or variation.
- the sender insists on that the respective contract is concluded only upon an express mutual agreement on all its aspects.
- the sender of this e-mail informs that he/she is not authorized to enter into any contracts on behalf of the company except for cases in which he/she is expressly authorized to do so in writing, and such authorization or power of attorney is submitted to the recipient or the person represented by the recipient, or the existence of such authorization is known to the recipient of the person represented by the recipient.

  
  


  


      

    

    

      
      

        


  

        

      Jeff Newmiller
    

    

      
      #
    

  


  

      
Date data cannot represent hour data. You need to use POSIXct or perhaps the chron class from the chron package. 

To use POSIXct, use ISOdatetime instead of ISOdate. Also be careful which timezone you have set as default (in most operating systems calling Sys.setenv(TZ="Etc/GMT") or similar will get you started) when you invoke ISOdatetime, since daylight savings can complicate things. Of course if daylight savings is built into your data already then  you are better off choosing a timezone that understands that. See ?DateTimeClasses.

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      Ogbos Okike
    

    

      
      #
    

  


  

      
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. 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:

            

      
      
      
    

        

      
      
    

            

      
      
      
    

  
  


  


      

    

    

      
      

        


  

        

      David Winsemius
    

    

      
      #
    

  


  

          

      
      
      
    

        
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.