PigWolf PigWolf - 1 year ago 219
R Question

read.csv2 date formatting in R

I wish to import my csv file into a data frame but the date in my csv file is in a non-standard format.

The date in the first column is in the following format:


One of the arguments in my read.csv2 functions is to specify the classes and when I specify this column as a date I receive the following error upon execution:

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

I'm guessing it doesn't like converting the date from factor class to date class.

I've read a little about POSIXlt but I don't understand the details of the function.

Any ideas how to convert the class from factor to date??

Answer Source

When you convert character to date, you need specify format if it is not standard. The error you got is the result of as.Date("08.09.2016"). But if you do as.Date("08.09.2016", format = "%m.%d.%Y"), it is fine.

I am not sure whether it is possible to pass format to read.csv2 for correct date formatting (maybe not). I would simply read in this date column as factor, then do as.Date(as.character(), format = "%m.%d.%Y") on this column myself.

Generally we use the following format "dd/mm/yy" how can I reorganise the date to that format?

Use format(, format = "%d/%m/%y").

A complete example:

format(as.Date("08.09.2016", format = "%m.%d.%Y"), format = "%d/%m/%y")
# [1] "09/08/16"
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