lubridate::floor_date()

Function of the Week:floor_date()

Martin Arrigotti

floor_date()

In this document, I will introduce the floor_date() function and show what it’s for.

#load tidyverse up
library(tidyverse)
## ── Attaching packages ─────────────────────────────────────── tidyverse 1.3.0 ──
## ✓ ggplot2 3.3.2     ✓ purrr   0.3.4
## ✓ tibble  3.0.4     ✓ dplyr   1.0.2
## ✓ tidyr   1.1.2     ✓ stringr 1.4.0
## ✓ readr   1.4.0     ✓ forcats 0.5.0
## ── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
## x dplyr::filter() masks stats::filter()
## x dplyr::lag()    masks stats::lag()
library(lubridate)
## 
## Attaching package: 'lubridate'
## The following objects are masked from 'package:base':
## 
##     date, intersect, setdiff, union
library(palmerpenguins)
library(janitor)
## 
## Attaching package: 'janitor'
## The following objects are masked from 'package:stats':
## 
##     chisq.test, fisher.test
data(penguins)
penguins<- clean_names(penguins_raw)

What is it for?

floor_date() is a relatively simple function that allows you to round a date value into a specified time precision level (so long as the date value contains that level of precision). So if you have a date that gives you the value in seconds, but you only want the year, you can do use floor_date() for that.

#example

# create a date variable with more than the desired level of specificity (I'll do the date and time of this class, with you being 21 seconds late)
# date is of the form  YYYY-MM-DD HH-MM-SS
x <- as.POSIXct("2021-02-17 15:15:21",tz="PT")

# lets say we only want to know what day class is on
x_days <- floor_date(x,"days")
x_days
## [1] "2021-02-17"
#for our penguins dataset
floor_date(penguins$date_egg, "years")
##   [1] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
##   [6] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
##  [11] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
##  [16] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
##  [21] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
##  [26] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
##  [31] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
##  [36] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
##  [41] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
##  [46] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
##  [51] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
##  [56] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
##  [61] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
##  [66] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
##  [71] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
##  [76] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
##  [81] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
##  [86] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
##  [91] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
##  [96] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
## [101] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [106] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [111] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [116] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [121] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [126] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [131] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [136] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [141] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [146] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [151] "2009-01-01" "2009-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
## [156] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
## [161] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
## [166] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
## [171] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
## [176] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
## [181] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
## [186] "2007-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
## [191] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
## [196] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
## [201] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
## [206] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
## [211] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
## [216] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
## [221] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
## [226] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
## [231] "2008-01-01" "2008-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [236] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [241] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [246] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [251] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [256] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [261] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [266] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [271] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [276] "2009-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
## [281] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
## [286] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
## [291] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
## [296] "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01" "2007-01-01"
## [301] "2007-01-01" "2007-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
## [306] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
## [311] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
## [316] "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01" "2008-01-01"
## [321] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [326] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [331] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [336] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"
## [341] "2009-01-01" "2009-01-01" "2009-01-01" "2009-01-01"

Is it helpful?

with the statistical work I’ve done so far, I don’t have much use for this. That said, if you have a study with hundreds or thousands of data points that used a computer program to report the date an event happened (so would likely record down to seconds), and you wanted to know total person-years/days/unit-of-time observed, this would be a very handy tool for getting your data into a format that shows only the most necessary information.

Last updated on March 12, 2021

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