How to Use strptime and strftime Functions in R

You can use the strptime and strftime functions in R to convert between character and time objects.

The strptime function converts characters to time objects and uses the following basic syntax:

strptime(character_object, format="%Y-%m-%d")

The strftime function converts time objects to characters and uses the following basic syntax:

strftime(time_object)

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

Example 1: Use strptime Function in R

Suppose we have the following character vector in R:

#create character vector
char_data <- c("2022-01-01", "2022-01-25", "2022-02-14", "2022-03-19")

#view class of vector
class(char_data)

[1] "character"

We can use the strptime function to convert the characters to time objects:

#convert characters to time objects
time_data <- strptime(char_data, format="%Y-%m-%d")

#view new vector
time_data

[1] "2022-01-01 UTC" "2022-01-25 UTC" "2022-02-14 UTC" "2022-03-19 UTC"

#view class of new vector
class(time_data)

[1] "POSIXlt" "POSIXt"

We can see that the characters have been converted to time objects.

Note that we can also use the tz argument to convert the characters to time objects with a specific time zone.

For example, we could specify “EST” to convert the characters to time objects in the Eastern Time Zone:

#convert characters to time objects in EST time zone
time_data <- strptime(char_data, format="%Y-%m-%d", tz="EST")

#view new vector
time_data

[1] "2022-01-01 EST" "2022-01-25 EST" "2022-02-14 EST" "2022-03-19 EST"

Notice that each of the time objects now end with EST, which indicates an Eastern Time Zone.

Example 2: Use strftime Function in R

Suppose we have the following vector of time objects in R:

#create vector of time objects
time_data <- as.POSIXct(c("2022-01-01", "2022-01-25", "2022-02-14"))

#view class of vector
class(time_data)

[1] "POSIXct" "POSIXt"

We can use the strftime function to convert the time objects to characters:

#convert time objects to characters
char_data <- strftime(time_data)

#view new vector
char_data

[1] "2022-01-01" "2022-01-25" "2022-02-14"

#view class of new vector
class(char_data)

[1] "character"

We can see that the time objects have been converted to characters.