Convert four digit year values to class Date

by

Based on the comments it turned out that the person asking the question did not need to change a numeric year to "Date" class; nevertheless, the question asked how to do it so here is an answer.

Here are a few ways to create a "Date" class object from a 4 digit numeric year. All use as.Date:

yrs <- c(2001, 2002, 2002, 2002, 2003, 2005)

1) ISOdate

as.Date(ISOdate(yrs, 1, 1))  # beginning of year
as.Date(ISOdate(yrs, 12, 31))  # end of year

This ISOdate solution is a bit tricky because it creates an intermediate POSIXct object so time zone problems could exist. You might prefer one of the following.

2) paste

as.Date(paste(yrs, 1, 1, sep = "-")) # beginning of year
as.Date(paste(yrs, 12, 31, sep = "-")) # end of year

3) zoo::as.yearmon 

library(zoo)

as.Date(as.yearmon(yrs)) # beginning of year
as.Date(as.yearmon(yrs) + 11/12, frac = 1) # end of year

Note: If y is the result for any of the above then format(y, "%Y") gives the character year and as.numeric(format(y, "%Y")) gives the numeric year.

More Related Contents:

  1. Convert date-time string to class Date
  2. How to convert Excel date format to proper date in R
  3. How to convert variable with mixed date formats to one format?
  4. Find the day of a week
  5. Specify custom Date format for colClasses argument in read.table/read.csv
  6. Get the difference between dates in terms of weeks, months, quarters, and years
  7. Converting year and month (“yyyy-mm” format) to a date?
  8. Number of months between two dates
  9. Subset a dataframe between 2 dates
  10. Find which season a particular date belongs to
  11. as.Date with dates in format m/d/y in R
  12. Add a month to a Date [duplicate]
  13. Convert integer to class Date
  14. as.Date returning NA while converting from ‘ddmmmyyyy’
  15. R: How to handle times without dates?
  16. Extract Month and Year From Date in R
  17. Extracting time from POSIXct
  18. Convert string to date, format: “dd.mm.yyyy”
  19. Format for ordinal dates (day of month with suffixes -st, -nd, -rd, -th)
  20. How can I fix corrupted dates in R?
  21. How to sort a data frame by date
  22. Convert yyyymmdd string to Date class in R
  23. Subsetting a dataframe for a specified month and year
  24. R group by date, and summarize the values
  25. format year-month to POSIXct [duplicate]
  26. Convert integer as “20160119” to different columns of “day” “year” “month”
  27. How to convert a date from a character string?
  28. Get date difference in years (floating point)
  29. Formatting a date in R without leading zeros
  30. Round a POSIX date (POSIXct) with base R functionality

Leave a Comment