I am running into trouble when trying to compare date fields in my dataset.
When I view a field, it looks like it is a date in 2011:
> alldata$new.date.local[1]
[1] "2011-07-01 12:08:07 EDT"
However, when I try to compare it to a character string, it seems to think it
is equal to sometime between the years 1310 and 1309
> alldata$new.date.local[1] < "1310-01-01 00:00:00 EDT"
[1] TRUE
> alldata$new.date.local[1] < "1309-12-31 23:59:59 EDT"
[1] FALSE
But not exactly equal to midnight of Dec 31 in 1309, so it is not equal to any
exact time:
> alldata$new.date.local[1] == "1309-12-31 23:59:59 EDT"
[1] FALSE
> alldata$new.date.local[1] < "1309-12-31 23:59:59 EDT"
[1] FALSE
> alldata$new.date.local[1] > "1309-12-31 23:59:59 EDT"
[1] TRUE
Even though this date field was created using as.POSIXct from a text string, I
have tried fixing this by reapplying the as.POSIXct function:
>alldata$new.date.local <- as.POSIXct(alldata$new.date.local, tz = "EDT")
But this does not seem to fix the problem. When I try recreating the date from
a character string I get the same behavior. Any suggestions would be much
appreciated.
-Heather
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