Hoeveel seconden zitten er in een dag?

Hoeveel seconden zitten er in een dag? Er zijn 24 uur in een dag, 60 minuten in een uur en 60 seconden in een minuut, dus zou je verwachten dat 24*60*60 = 86400 seconden, toch?

Niet altijd! In deze oefening zie je een tegenvoorbeeld. Kun je achterhalen wat er gebeurt?

Deze oefening maakt deel uit van de cursus

Werken met datums en tijden in R

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Oefeninstructies

We hebben code toegevoegd die drie tijdstippen definieert in je script: 12.00 uur (noon) op 11, 12 en 13 maart 2017 in de Amerikaanse Pacific-tijdzone.

Bereken het tijdsverschil tussen mar_13 en mar_12 in seconden. Dit zou overeen moeten komen met je intuïtie.
Bereken nu het tijdsverschil tussen mar_12 en mar_11 in seconden. Verrast?

Praktische interactieve oefening

Probeer deze oefening eens door deze voorbeeldcode in te vullen.

# Three dates
mar_11 <- ymd_hms("2017-03-11 12:00:00", 
  tz = "America/Los_Angeles")
mar_12 <- ymd_hms("2017-03-12 12:00:00", 
  tz = "America/Los_Angeles")
mar_13 <- ymd_hms("2017-03-13 12:00:00", 
  tz = "America/Los_Angeles")

# Difference between mar_13 and mar_12 in seconds
difftime(___, ___, units = ___)

# Difference between mar_12 and mar_11 in seconds
difftime(___, ___, units = ___)

Code bewerken en uitvoeren

Deze oefening maakt deel uit van de cursus

Werken met datums en tijden in R

SkillTag.level.intermediateSkillTag.label

4.8+

Begin de cursus gratis

R doesn't know something is a date or time unless you tell it. In this chapter you'll learn about some of the ways R stores dates and times by exploring how often R versions are released, and how quickly people download them. You'll also get a sneak peek at what you'll learn in the following chapters.

Exercise 1: Introduction to dates Exercise 2: Recognizing ISO 8601 dates Exercise 3: Specifying dates Exercise 4: Automatic import Exercise 5: Why use dates?Exercise 6: Plotting Exercise 7: Arithmetic and logical operators Exercise 8: What about times?Exercise 9: Getting datetimes into R Exercise 10: Datetimes behave nicely too Exercise 11: Why lubridate?

Dates and times come in a huge assortment of formats, so your first hurdle is often to parse the format you have into an R datetime. This chapter teaches you to import dates and times with the lubridate package. You'll also learn how to extract parts of a datetime. You'll practice by exploring the weather in R's birthplace, Auckland NZ.

Exercise 1: Parsing dates with lubridate Exercise 2: Selecting the right parsing function Exercise 3: Specifying an order with `parse_date_time()`Exercise 4: Weather in Auckland Exercise 5: Import daily weather data Exercise 6: Import hourly weather data Exercise 7: Extracting parts of a datetime Exercise 8: What can you extract?Exercise 9: Adding useful labels Exercise 10: Extracting for plotting Exercise 11: Extracting for filtering and summarizing Exercise 12: Rounding datetimes Exercise 13: Practice rounding Exercise 14: Rounding with the weather data

Getting datetimes into R is just the first step. Now that you know how to parse datetimes, you need to learn how to do calculations with them. In this chapter, you'll learn the different ways of representing spans of time with lubridate and how to leverage them to do arithmetic on datetimes. By the end of the chapter, you'll have calculated how long it's been since the first man stepped on the moon, generated sequences of dates to help schedule reminders, calculated when an eclipse occurs, and explored the reigns of monarch's of England (and which ones might have seen Halley's comet!).

Exercise 1: Verschillen tussen datetimes berekenen Exercise 2: Hoe lang is het geleden?Exercise 3: Hoeveel seconden zitten er in een dag?

Huidige oefening

Exercise 4: Tijdspannen.Exercise 5: Een tijdspanne optellen bij of aftrekken van een datetime Exercise 6: Duur of periode?Exercise 7: Rekenen met tijdsspannen Exercise 8: Reeksen van datetimes genereren Exercise 9: Het lastige aan maanden Exercise 10: Intervallen Exercise 11: Intervallen onderzoeken. Regeerperiodes van koningen en koninginnen Exercise 12: Intervallen en datetimes vergelijken Exercise 13: Converteren naar durations en periods

You now know most of what you need to tackle data that includes dates and times, but there are a few other problems you might encounter in practice. In this final chapter you'll learn a little more about these problems by returning to some of the earlier data examples and learning how to handle time zones, deal with times when you don't care about dates, parse dates quickly, and output dates and times.

Exercise 1: Time zones Exercise 2: Setting the timezone Exercise 3: Viewing in a timezone Exercise 4: Timezones in the weather data Exercise 5: Times without dates Exercise 6: More on importing and exporting datetimes Exercise 7: Fast parsing with fasttime Exercise 8: Fast parsing with lubridate::fast_strptime Exercise 9: Outputting pretty dates and times Exercise 10: Wrap-up