Create and format dates
To create a Date object from a simple character string in R, you can use the as.Date() function. The character string has to obey a format that can be defined using a set of symbols (the examples correspond to 13 January, 1982):
%Y: 4-digit year (1982)%y: 2-digit year (82)%m: 2-digit month (01)%d: 2-digit day of the month (13)%A: weekday (Wednesday)%a: abbreviated weekday (Wed)%B: month (January)%b: abbreviated month (Jan)
The following R commands will all create the same Date object for the 13th day in January of 1982:
as.Date("1982-01-13")
as.Date("Jan-13-82", format = "%b-%d-%y")
as.Date("13 January, 1982", format = "%d %B, %Y")
Notice that the first line here did not need a format argument, because by default R matches your character string to the formats "%Y-%m-%d" or "%Y/%m/%d".
In addition to creating dates, you can also convert dates to character strings that use a different date notation. For this, you use the format() function. Try the following lines of code:
today <- Sys.Date()
format(Sys.Date(), format = "%d %B, %Y")
format(Sys.Date(), format = "Today is a %A!")
This is a part of the course
“Intermediate R”
Exercise instructions
- Three character strings representing dates have been created for you. Convert them to dates using
as.Date(), and assign them todate1,date2, anddate3respectively. The code fordate1is already included. - Extract useful information from the dates as character strings using
format(). From the first date, select the weekday. From the second date, select the day of the month. From the third date, you should select the abbreviated month and the 4-digit year, separated by a space.
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Definition of character strings representing dates
str1 <- "May 23, '96"
str2 <- "2012-03-15"
str3 <- "30/January/2006"
# Convert the strings to dates: date1, date2, date3
date1 <- as.Date(str1, format = "%b %d, '%y")
# Convert dates to formatted strings
format(date1, "%A")This exercise is part of the course
Intermediate R
Continue your journey to becoming an R ninja by learning about conditional statements, loops, and vector functions.
Mastering R programming is not only about understanding its programming concepts. Having a solid understanding of a wide range of R functions is also important. This chapter introduces you to many useful functions for data structure manipulation, regular expressions, and working with times and dates.
Exercise 1: Useful FunctionsExercise 2: Mathematical utilitiesExercise 3: Find the errorExercise 4: Data UtilitiesExercise 5: Find the error (2)Exercise 6: Beat Gauss using RExercise 7: Regular ExpressionsExercise 8: grepl & grepExercise 9: grepl & grep (2)Exercise 10: sub & gsubExercise 11: sub & gsub (2)Exercise 12: Times & DatesExercise 13: Right here, right nowExercise 14: Create and format datesExercise 15: Create and format timesExercise 16: Calculations with DatesExercise 17: Calculations with TimesExercise 18: Time is of the essenceWhat is DataCamp?
Learn the data skills you need online at your own pace—from non-coding essentials to data science and machine learning.