convert factor date 1/1/2017 to 2017-01

Question

I have a column currentdate with date in class factor and formatted as 1/1/2017. I want to convert the dates to 2017-01. My code below gives and error:

Code:

data$NewDate <- format(as.Date(data$currentdate), "%Y-%m")

Error:

Error in charToDate(x) : character string is not in a standard unambiguous format

How do I fix that?

Or refer to this question: https://stackoverflow.com/questions/15316657/convert-date-to-year-month-representation-in-r — yusuzech, May 25 '18 at 23:30

score 0 · Answer 1 · answered May 25 '18 at 23:34

0

It's likely that your data$currentdate is not in a unambiguous format, and needs to be specified in the as.Date().

Something like this:

format(as.Date("01/01/2017", format="%m/%d/%Y"), "%Y-%m")

answered May 25 '18 at 23:34

John Harley

156
1
6

Carlos Eduardo Lagosta · Answer 2 · 2018-05-26T00:30:00.897

You need to specify the date format in as.Date(), since it cannot guess by the numbers if it's day/month/year or month/day/year:

dates <- c('1/1/2017', '12/1/2017', '1/10/2017', '11/10/2017')

format(as.Date(dates, '%d/%m/%Y'), '%Y-%m')

If you need to store the values as date/time, use class POSIXct:

newdates <- as.POSIXct(dates, format = '%d/%m/%Y')

Then specify the format when displaying the data:

format(newdates, '%Y-%m')

convert factor date 1/1/2017 to 2017-01

2 Answers2