How to change default “date” format in R?

[andrii]

The default R date format is "yyyy-mm-dd".

Let say I have dataset

library(data.table)

dt_test <- data.table(
  date = c("01.03.2019", "02.03.2019"),
  value = c(1, 2))

where "date" is "chr" type.

I'd like to have it as "Date" feature and set default date format as "%d.%m.%Y".

And, also to keep this format for all "ggplot" operations.

Thanks all ahead!

[martin.R]

Dates are actually stored as integers. The format options are for printing, not for storing the date values.

dt_test <- data.table(
  date = as.Date(c("01.03.2019", "02.03.2019"), format = "%d.%m.%Y"), 
  value = c(1, 2))

You will have to define your desired date format when you want to display the date values, e.g. in your plots. You can use the format above or use lubridate.

[andresrcs]

@andrii

And, also to keep this format for all "ggplot" operations.

You can specify your date format in ggplot with scale_x_date()

library(data.table)
library(ggplot2)
dt_test <- data.table(
    date = as.Date(c("01.03.2019", "02.03.2019"), format = "%d.%m.%Y"), 
    value = c(1, 2))
ggplot(dt_test, aes(date, value)) +
    geom_line()+
    scale_x_date(date_labels = '%d.%m.%Y')