Create and format times

Similar to working with dates, you can use as.POSIXct() to convert from a character string to a POSIXct object, and format() to convert from a POSIXct object to a character string. Again, you have a wide variety of symbols:

%H: hours as a decimal number (00-23)
%I: hours as a decimal number (01-12)
%M: minutes as a decimal number
%S: seconds as a decimal number
%T: shorthand notation for the typical format %H:%M:%S
%p: AM/PM indicator

For a full list of conversion symbols, consult the strptime documentation in the console:

?strptime

Again,as.POSIXct() uses a default format to match character strings. In this case, it's %Y-%m-%d %H:%M:%S. In this exercise, abstraction is made of different time zones.

This exercise is part of the course

Intermediate R

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Exercise instructions

Convert two strings that represent timestamps, str1 and str2, to POSIXct objects called time1 and time2.
Using format(), create a string from time1 containing only the minutes.
From time2, extract the hours and minutes as "hours:minutes AM/PM". Refer to the assignment text above to find the correct conversion symbols!

Hands-on interactive exercise

Have a go at this exercise by completing this sample code.

# Definition of character strings representing times
str1 <- "May 23, '96 hours:23 minutes:01 seconds:45"
str2 <- "2012-3-12 14:23:08"

# Convert the strings to POSIXct objects: time1, time2
time1 <- as.POSIXct(str1, format = "%B %d, '%y hours:%H minutes:%M seconds:%S")


# Convert times to formatted strings

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