CODEWITHSUNDEEP
rdplyr
Kobe_77
Kobe_77

Reputation: 1

nested functions: Arrange() and desc()

With gapminder being a tibble and lifeExp being a variable name in gapminder, I tried using two functions arrange() and desc().

This works:

gapminder %>% arrange(desc(lifeExp))

This does not work:

gapminder %>% desc(arrange(lifeExp)

Error: unused argument (arrange(lifeExp))

I am not sure why, any help with be much appreciated.

Upvotes: 0

Views: 384

Answers (2)

cnbrownlie
cnbrownlie

Reputation: 632

The previous answer is more or less right but the reason for this is due to the nature of the piping operator %>%.

The pipe takes whatever is to the left and passes it as the first argument to the function on the right. If you look at the documentation for dplyr::desc you can see it only takes a single argument x (the vector to be arranged), so your second example is equivalent to

desc(gapminder, arrange(lifeExp))

and R is seeing two arguments where it expects one (hence the error message).

arrange() on the other hand accepts two arguments, so your first example which is equivalent to:

arrange(gapminder, desc(lifeExp))

works, as R is expecting two arguments to arrange() and that is what it sees.

Upvotes: 1

Sergio A. Gottret Rios
Sergio A. Gottret Rios

Reputation: 11

I'm also new on this, but it seems that the grammar is different in each line of code.

gapminder %>% arrange(desc(lifeExp)) # is read like "the tibble gapminder", "then" "arrange" it "in descendant values" of "lifeExp"

gapminder %>% desc(arrange(lifeExp) # is read like "the tibble gapminder", "then" "in descendant order" "arrange it" by "lifeExp". The arrange command is for a tibble, while a desc is for aiming at one variable.

Espero me haya hecho entender bro

Upvotes: 1

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