Date formats and extractor functions
Intermediate R for Finance
Lore Dirick
Manager of Data Science Curriculum at Flatiron School
Date formats
# ISO 8601 Standard: year-month-day
as.Date("2017-01-28")
"2017-01-28"
# Alternative form: year/month/day
as.Date("2017/01/28")
"2017-01-28"
# Fails: month/day/year
as.Date("01/28/2017")
Error in charToDate(x) :
character string is not in
a standard unambiguous format
# Explicitly tell R the format
as.Date("01/28/2017", format = "%m/%d/%Y")
"2017-01-28"
Date formats
| Format | Description |
|---|---|
| %d | Day of the month (01-31) |
| %m | Month (01-12) |
| %y | Year without century (00-99) |
| %Y | Year with century (0-9999) |
| %b | Abbreviated month name |
| %B | Full month name |
| / - , | Common separators |
Date formats
| Format | Description |
|---|---|
| %d | Day of the month (01-31) |
| %m | Month (01-12) |
| %y | Year without century (00-99) |
| %Y | Year with century (0-9999) |
| %b | Abbreviated month name |
| %B | Full month name |
| / - , | Common separators |
Date formats
| Format | Description |
|---|---|
| %d | Day of the month (01-31) |
| %m | Month (01-12) |
| %y | Year without century (00-99) |
| %Y | Year with century (0-9999) |
| %b | Abbreviated month name |
| %B | Full month name |
| / - , | Common separators |
Date formats
| Format | Description |
|---|---|
| %d | Day of the month (01-31) |
| %m | Month (01-12) |
| %y | Year without century (00-99) |
| %Y | Year with century (0-9999) |
| %b | Abbreviated month name |
| %B | Full month name |
| / - , | Common separators |
Date formats
| Format | Description |
|---|---|
| %d | Day of the month (01-31) |
| %m | Month (01-12) |
| %y | Year without century (00-99) |
| %Y | Year with century (0-9999) |
| %b | Abbreviated month name |
| %B | Full month name |
| / - , | Common separators |
Date format example
| Format | Description |
|---|---|
| %d | Day of the month (01-31) |
| %Y | Year with century (0-9999) |
| %B | Full month name |
| / - , | Common separators |
# Lehman Brothers bankruptcy
# Complex format - what do we use?
as.Date("September 15, 2008", format = "___")
as.Date("September 15, 2008", format = "%B %d, %Y")
"2008-09-15"
Extractor functions
dates <- as.Date(c("2017-01-03", "2017-01-04"))
weekdays(dates)
"Tuesday" "Wednesday"
Let's practice!
Intermediate R for Finance
