I imported a CSV file with dates from a SQL query, but the dates are really date-time values and R doesn't seem to recognize them as dates:
> mydate
[1] 1/15/2006 0:00:00
2373 Levels: 1/1/2006 0:00:00 1/1/2007 0:00:00 1/1/2008 0:00:00 ... 9/9/2012 0:00:00
> class(mydate)
[1] "factor"
> as.Date(mydate)
Error in charToDate(x) :
character string is not in a standard unambiguous format
How do I convert mydate
to date format? (I don't need to include the time portion.)
You were close. format=
needs to be added to the as.Date
call:
mydate <- factor("1/15/2006 0:00:00")
as.Date(mydate, format = "%m/%d/%Y")
## [1] "2006-01-15"
You can try lubridate package which makes life much easier
library(lubridate)
mdy_hms(mydate)
The above will change the date format to POSIXct
A sample working example:
> data <- "1/15/2006 01:15:00"
> library(lubridate)
> mydate <- mdy_hms(data)
> mydate
[1] "2006-01-15 01:15:00 UTC"
> class(mydate)
[1] "POSIXct" "POSIXt"
For case with factor use as.character
data <- factor("1/15/2006 01:15:00")
library(lubridate)
mydate <- mdy_hms(as.character(data))
Take a look at the formats in ?strptime
R> foo <- factor("1/15/2006 0:00:00")
R> foo <- as.Date(foo, format = "%m/%d/%Y %H:%M:%S")
R> foo
[1] "2006-01-15"
R> class(foo)
[1] "Date"
Note that this will work even if foo
starts out as a character. It will also work if using other date formats ( as.POSIXlt
, as.POSIXct
).
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