How to Convert Date to Numeric in R (With Examples)


There are two methods you can use to convert date values to numeric values in R:

Method 1: Use as.numeric()

as.numeric(my_date)

This will return the number of seconds that have passed between your date object and 1/1/1970.

Method 2: Use Functions from the lubridate package

library(lubridate)

#get seconds value in date object
second(my_date)

#get minutes value in date object
minute(my_date)

...
#get year value in date object
year(my_date)

This will return the value for the seconds, minutes, years, etc. from your date object.

The following examples show how to use each method in practice.

Method 1: Use as.numeric()

The following code shows how to convert a date object to numeric using the as.numeric() function:

#create date object
my_date <- as.POSIXct("10/14/2021  5:35:00 PM", format="%m/%d/%Y  %H:%M:%S %p")

#view date object
my_date

[1] "2021-10-14 05:35:00 UTC"

#convert date object to number of seconds since 1/1/1970
as.numeric(my_date)

[1] 1634189700

#convert date object to number of days since 1/1/1970
as.numeric(my_date) / 86400

[1] 18914.23

#convert date object to number of years since 1/1/1970
as.numeric(my_date) / 86400 / 365

[1] 51.81982

Based on the output we can see:

  • There is a difference of 1,634,189,700 seconds between our date object and 1/1/1970.
  • There is a difference of 18,914.23 days between our date object and 1/1/1970.
  • There is a difference of 51.81982 years between our date object and 1/1/1970.

Method 2: Use Functions from the lubridate Package

The following code shows how to convert a date object to numeric using functions from the lubridate package in R:

library(lubridate)

#create date object
my_date <- as.POSIXct("10/14/2021  5:35:00 PM", format="%m/%d/%Y  %H:%M:%S %p")

#view date object
my_date

[1] "2021-10-14 05:35:00 UTC"

#extract various numerical values from date object
second(my_date)

[1] 0

minute(my_date)

[1] 35

hour(my_date)

[1] 5

day(my_date)

[1] 14

month(my_date)

[1] 10

year(my_date)

[1] 2021

Using these functions, we can extract the seconds, minutes, hours, days, months, and year values from our date object.

Refer to this online cheat sheet to gain a complete understanding of the most commonly used functions in the lubridate package.

Additional Resources

The following tutorials explain how to perform other common conversions in R:

How to Convert a String to Datetime in R
How to Convert Numbers to Dates in R
How to Sort a Data Frame by Date in R

Leave a Reply

Your email address will not be published.