Convert tibble to xts for analysis with performanceanalytics package - r

Question

I have a tibble with a date and return column, that looks as follows:
> head(return_series)
# A tibble: 6 x 2
date return
<chr> <dbl>
1 2002-01 0.0292
2 2002-02 0.0439
3 2002-03 0.0240
4 2002-04 0.00585
5 2002-05 -0.0169
6 2002-06 -0.0686
I first add the day to the date column with the following code:
return_series$date <- as.Date(as.yearmon(return_series$date))
# A tibble: 6 x 2
date return
<date> <dbl>
1 2002-01-01 0.0292
2 2002-02-01 0.0439
3 2002-03-01 0.0240
4 2002-04-01 0.00585
5 2002-05-01 -0.0169
6 2002-06-01 -0.0686
My goal is to convert the return_series tibble to xts data to use it for further analysis with the PerformanceAnalytics package. But when I use the command as.xts I receive the following error:
Error in as.POSIXlt.character(x, tz, ...) :
character string is not in a standard unambiguous format
How can I change the format to xts or is there an other possibility to work with the PerformanceAnalytics package instead of converting to xts?
Thank you very much for your help!

Answer 1

You need to follow the xts documentation more closely:
> tb <- as_tibble(data.frame(date=as.Date("2002-01-01") + (0:5)*30,
+ return=rnorm(6)))
> tb
# A tibble: 6 × 2
date return
<date> <dbl>
1 2002-01-01 0.223
2 2002-01-31 -0.352
3 2002-03-02 0.149
4 2002-04-01 1.42
5 2002-05-01 -1.04
6 2002-05-31 0.507
>
> x <- xts(tb[,-1], order.by=as.POSIXct(tb[[1]]))
> x
return
2001-12-31 18:00:00 0.222619
2002-01-30 18:00:00 -0.352288
2002-03-01 18:00:00 0.149319
2002-03-31 18:00:00 1.421967
2002-04-30 19:00:00 -1.035087
2002-05-30 19:00:00 0.507046
>
An xts object prefers a POSIXct datetime object, which you can convert from a Date object. For a (closely-related) zoo object you could keep Date.