R-在data.frame中转换日期

Question

I am working with a " data.frame " which are given in the following formate: Aug 12, 2017.

class(data[,1]) = factor

How can i convert these into dates?

data[,1] <- as.Date.factor(data[,1],format = "%m.%d.%y") , returns NA 's.

Answer 1

I would suggest the package lubridate for very easy to use functions to operate with dates. For example:

mdy("Aug 12,2017")
[1] "2017-08-12"

If your date is in YYYY-MM-DD format, you can use the ymd function. There are also other functions such as dmy , dmy_hms (for datetime), etc.

If your column is called my.date , you can do:

data$my.date <- mdy(data$my.date)

Alternatively, you can use the %<>% operator from magrittr to make your code even shorter:

data$my.date %<>% mdy

Answer 2

Use as.POSIXct (Base-R Solution):

as.POSIXct("Aug 12,2017", format="%b%d,%Y")

Output:

[1] "2017-08-12 CEST"

Answer 3

Using strptime , could work:

strptime("Aug 12,2017", "%b%d,%Y")

Output:

[1] "2017-08-12 UTC"

The second parameter for strptime is the format of the dates you have. For instance, if your dates are like this "1/5/2005" , then the format would be:

format="%m/%d/%Y"

Hope it helps