Functiehulp en documentatie

Als je niet weet hoe je een functie moet gebruiken, of niet weet welke argumenten erbij horen, waar kun je dan terecht? Gelukkig heeft R ingebouwde documentatie. Om bijvoorbeeld hulp te krijgen voor de functie names(), kun je een van de volgende typen:

?names

?names()

help(names)

Deze doen allemaal hetzelfde: ze brengen je direct naar de helppagina van names()!

In de DataCamp-console word je doorgestuurd naar de RDocumentation-site voor hulp, maar de informatie is precies hetzelfde!

Hieronder ga je de documentatie voor een paar andere functies verkennen.

Deze oefening maakt deel uit van de cursus

R voor finance voor gevorderden

Cursus bekijken

Oefeninstructies

Gebruik ? om de documentatie van subset() te bekijken.
Gebruik ? om de documentatie van Sys.time() te bekijken.

Praktische interactieve oefening

Probeer deze oefening eens door deze voorbeeldcode in te vullen.

# Look at the documentation for subset
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# Look at the documentation for Sys.time
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Code bewerken en uitvoeren

Deze oefening maakt deel uit van de cursus

R voor finance voor gevorderden

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Begin de cursus gratis

Welcome! Before we go deeper into the world of R, it will be nice to have an understanding of how dates and times are created. This chapter will teach you enough to begin working with dates, but only scratches the surface of what you can do with them.

Exercise 1: An introduction to dates in R Exercise 2: What day is it?Exercise 3: From char to date Exercise 4: Many dates Exercise 5: Date formats and extractor functions Exercise 6: Date formats (1)Exercise 7: Date formats (2)Exercise 8: Subtraction of dates Exercise 9: months() and weekdays() and quarters(), oh my!

Imagine you own stock in a company. If the stock goes above a certain price, you might want to sell. If the stock drops below a certain price, you might want to buy it while it's cheap! This kind of thinking can be implemented using operators and if statements. In this chapter, you will learn all about them, and create a program that tells you to buy or sell a stock.

Exercise 1: Relational operators Exercise 2: Relational practice Exercise 3: Vectorized operations Exercise 4: Logical operators Exercise 5: And / Or Exercise 6: Not!Exercise 7: Logicals and subset()Exercise 8: All together now!Exercise 9: If statements Exercise 10: If this Exercise 11: If this, Else that Exercise 12: If this, Else If that, Else that other thing Exercise 13: Can you If inside an If?Exercise 14: ifelse()

Loops can be useful for doing the same operation to each element of your data structure. In this chapter you will learn all about repeat, while, and for loops!

Exercise 1: Repeat loops Exercise 2: Repeat, repeat, repeat Exercise 3: When to break?Exercise 4: While loops Exercise 5: While with a print Exercise 6: While with a plot Exercise 7: Break it Exercise 8: For loops Exercise 9: Loop over a vector Exercise 10: Loop over data frame rows Exercise 11: Loop over matrix elements Exercise 12: Break and next

If data structures like data frames and vectors are how you hold your data, functions are how you tell R what to do with your data. In this chapter, you will learn about using built-in functions, creating your own unique functions, and you will finish off with a brief introduction to packages.

Exercise 1: Wat zijn functies?Exercise 2: Functiehulp en documentatie

Huidige oefening

Exercise 3: Optionele argumenten Exercise 4: Functies in functies Exercise 5: Functies schrijven Exercise 6: Je eerste functie Exercise 7: Meerdere argumenten (1)Exercise 8: Meerdere argumenten (2)Exercise 9: Functie-scope (1)Exercise 10: Functie-scope (2)Exercise 11: Packages Exercise 12: tidyquant-pakket

A popular alternative to loops in R are the apply functions. These are often more readable than loops, and are incredibly useful for scaling the data science workflow to perform a complicated calculation on any number of observations. Learn about them here!

Exercise 1: Why use apply?Exercise 2: lapply() on a list Exercise 3: lapply() on a data frame Exercise 4: FUN arguments Exercise 5: sapply() - simplify it!Exercise 6: sapply() vs. lapply()Exercise 7: Failing to simplify Exercise 8: vapply() - specify your output!Exercise 9: vapply() vs. sapply()Exercise 10: More vapply()Exercise 11: Anonymous functions Exercise 12: Congratulations