From char to date

You will often have to create dates yourself from character strings. The as.Date() function is the best way to do this:

# The Great Crash of 1929
great_crash <- as.Date("1929-11-29")

great_crash
[1] "1929-11-29"

class(great_crash)
[1] "Date"

Notice that the date is given in the format of "yyyy-mm-dd". This is known as ISO format (ISO = International Organization for Standardization), and is the way R accepts and displays dates.

Internally, dates are stored as the number of days since January 1, 1970, and datetimes are stored as the number of seconds since then. You will confirm this in the exercises below.

Create a date variable named crash for "2008-09-29", the date of the largest stock market point drop in a single day.
Print crash.
Use as.numeric() on crash to convert it to the number of days since January 1, 1970.
Wrap as.numeric() around Sys.time() to see the current time in number of seconds since January 1, 1970.
Attempt to create a date from "09/29/2008". What happens?

Exercise

From char to date

Instructions