[R] Changing date format

[PIKAL Petr]

Hi

But It is not doing what you wanted.  It does not extend 365 days year to 366 days. Instead it will incorrectly rename all days after 28th February in non leap years

> format(strptime(59, format = "%j"), "%d-%b")
[1] "28-II"
> format(strptime(60, format = "%j"), "%d-%b")
[1] "01-III"
> format(strptime(61, format = "%j"), "%d-%b")
[1] "02-III"
> day(59)
[1] "28-II"
> day(60)
[1] "29 Feb"
> day(61)
[1] "01-III"

So the effect is that day 61 in 2014 which actually was 2nd of March after your function will be named 1st of March. As a result it will remove 31.December in non leap year as in that case you do not have 366th day.

I did not follow whole thread but my vague memory reminds me that you want change number of days for aligning with some data. I do not believe that anybody violates calendar in such a way that all years have 366 days.

I may be mistaken but isn’t ?merge function what you really want?

Petr


From: Frederic Ntirenganya [mailto:ntfredo at gmail.com]
Sent: Friday, October 10, 2014 8:33 AM
To: Duncan Murdoch
Cc: PIKAL Petr; r-help at r-project.org
Subject: Re: [R] Changing date format

Dear All,
The following function gives me what I wanted.
The input of function is one value and this push me to use sapply function to call it.

Is there a better way of doing this?
#====================================================
day <- function(x){

         if(x== 60) {
               y = "29 Feb"
         }

         if(x < 60){
                y =  format(strptime(x, format = "%j"), format ="%d-%b")
        }

        if(x > 60){
                y =  format(strptime(x - 1, format = "%j"), format ="%d-%b")
       }
    y
}

sapply(Samaru$Start,day)

 [1] "17-Apr" "27-Apr" "24-Apr" "04-Jun" "25-Apr" "13-May" "22-Apr" "05-May" "27-Apr" "13-May" "27-Apr"
#=======================================================

On Thu, Oct 9, 2014 at 3:48 PM, Duncan Murdoch <murdoch.duncan at gmail.com<mailto:murdoch.duncan at gmail.com>> wrote:
On 09/10/2014, 8:27 AM, PIKAL Petr wrote:
> Hi
>
>> -----Original Message-----
>> From: r-help-bounces at r-project.org<mailto:r-help-bounces at r-project.org> [mailto:r-help-bounces at r-<mailto:r-help-bounces at r->
>> project.org<http://project.org>] On Behalf Of Frederic Ntirenganya
>> Sent: Thursday, October 09, 2014 1:32 PM
>> To: Jim Lemon
>> Cc: r-help at r-project.org<mailto:r-help at r-project.org>
>> Subject: Re: [R] Changing date format
>>
>> This idea substract 1 for the all column which is not what i want.
>>
>> We know that the leap years have 366 days. I don't need to change
>> anything on them
>>
>> the non-leap years have 365 days. This is what i want to change to be
>> 366 days rather than 365 days.
>
> But this is a question of calendar reform not R. I must admit it would be a tough job as leap day is needed to stay in tune with solar year. Your suggestion would quickly result in out of sync with the Sun.

R Core is powerful, but I doubt if we could reform the calendar in this
way.

And I'd be against it in any case:  I like to swim on my summer
vacations, but if August slipped into the winter, the lakes around here
would be frozen.

Duncan Murdoch



--
Frederic Ntirenganya
Maseno University,
Kenya.
Mobile:(+254)718492836
Email: fredo at aims.ac.za<mailto:fredo at aims.ac.za>
https://sites.google.com/a/aims.ac.za/fredo/

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