[R] Incorrect Conversion of Datetime

[Enrico Schumann]

Quoting Ogbos Okike <giftedlife2014 using gmail.com>:

> Dear Friends,
> A sample of my data is:
> 98 05 01 02    8541
> 98 05 01 03    8548
> 98 05 01 04    8512
> 98 05 01 05    8541
> 98 05 01 06    8509
> 98 05 01 07    8472
> 98 05 01 08    8454
> 98 05 01 09    8461
> 98 05 01 10    8462
> 98 05 01 11    8475
> 98 05 01 12    8433
> 98 05 01 13    8479
> 98 05 01 14    8417
> 98 05 01 15    8463
> 98 05 01 16    8473
> 98 05 01 17    8450
> 98 05 01 18    8433
> 98 05 01 19    8437
> 98 05 01 20    8437
> 98 05 01 21    8438
> 98 05 01 22    8421
> 98 05 01 23    8420
> 98 05 02 00    8371
> 98 05 02 01    8338
> 98 05 02 02    8251
> 98 05 02 03    8204
> 98 05 02 04    8183
> 98 05 02 05    8231
> 98 05 02 06    8242
> Columns 1, 2, 3, 4 and 5 stands for year, month, day , hour and count.
>
> Using:
> Sys.setenv( TZ="GMT" )
>
>
> dta <- read.table("Ohr1may98", col.names = c("year", "month", "day",
> "hour", "counts"))
> dta$year <- with( dta, ifelse(year < 50, year + 2000, year + 1900))
> dta$datetime <- with( dta, as.POSIXct(ISOdatetime(year, month,day,hour,0,0)))
> a =  dta$datetime
> I converted the datetime and plotted the graph of count vs a. The plot
> was great but I have issues with the date.
>
> The raw data is for some hours for Ist and second day of may 1998 as
> is evident from the sample data. But the result of date stored in "a"
> above shows:
>> a
>  [1] "1998-01-05 02:00:00 GMT" "1998-01-05 03:00:00 GMT"
>  [3] "1998-01-05 04:00:00 GMT" "1998-01-05 05:00:00 GMT"
>  [5] "1998-01-05 06:00:00 GMT" "1998-01-05 07:00:00 GMT"
>  [7] "1998-01-05 08:00:00 GMT" "1998-01-05 09:00:00 GMT"
>  [9] "1998-01-05 10:00:00 GMT" "1998-01-05 11:00:00 GMT"
> [11] "1998-01-05 12:00:00 GMT" "1998-01-05 13:00:00 GMT"
> [13] "1998-01-05 14:00:00 GMT" "1998-01-05 15:00:00 GMT"
> [15] "1998-01-05 16:00:00 GMT" "1998-01-05 17:00:00 GMT"
> [17] "1998-01-05 18:00:00 GMT" "1998-01-05 19:00:00 GMT"
> [19] "1998-01-05 20:00:00 GMT" "1998-01-05 21:00:00 GMT"
> [21] "1998-01-05 22:00:00 GMT" "1998-01-05 23:00:00 GMT"
> [23] "1998-01-06 00:00:00 GMT" "1998-01-06 01:00:00 GMT"
> [25] "1998-01-06 02:00:00 GMT" "1998-01-06 03:00:00 GMT"
> [27] "1998-01-06 04:00:00 GMT" "1998-01-06 05:00:00 GMT"
> [29] "1998-01-06 06:00:00 GMT"
> This seems to suggest day 5 and 6 in January 1998 instead of day 1 and
> 2 in May of 1998.
>
> I have spent some time trying to resolve this but I have not been successful.
>
> I would be thankful if you could help me to check where I went astray.
>
> Thank you.
> Best wishes
> Ogbos
>

I cannot reproduce these results. Could you please provide a fully
reproducible example, by providing a small example dataset via 'dput(dta)'?


-- 
Enrico Schumann
Lucerne, Switzerland
http://enricoschumann.net