CODEWITHSUNDEEP
rdplyrpipingmagrittr
agenis
agenis

Reputation: 8377

Chain arithmetic operators in dplyr with %>% pipe

I would like to understand why, in the the dplyr or magrittr package, and more specifically the chaining function %>% has some trouble with the basic operators +, -, *, and /

Chaining takes the output of previous statement and feeds it as first argument of the next:

1:10 %>% sum
# [55]

Thus how come this doesn't work

1:10 %>%  *2 %>% sum
1:10 %>% .*2 %>% sum

I also found that the following syntax works for adding/substracting, but not multiply or divide. why so?

1:10 %>% +(2) # works OK
1:10 %>% *(2) # nope...

So should I write an anonymous function even to do a *2 operation on my data.frame?

1:10 %>% (function(x) x*2) %>% sum

Thanks, I couldn't find the answer in other SO questions.

Upvotes: 49

Views: 13617

Answers (4)

Brandon Rose MD MPH
Brandon Rose MD MPH

Reputation: 712

Thought I'd share the magrittr documentation so you could see all of your options!

Currently implemented aliases are...

extract `[`
extract2    `[[`
inset   `[<-`
inset2  `[[<-`
use_series  `$`
add `+`
subtract    `-`
multiply_by `*`
raise_to_power  `^`
multiply_by_matrix  `%*%`
divide_by   `/`
divide_by_int   `%/%`
mod `%%`
is_in   `%in%`
and `&`
or  `|`
equals  `==`
is_greater_than `>`
is_weakly_greater_than  `>=`
is_less_than    `<`
is_weakly_less_than `<=`
not (`n'est pas`)   `!`
set_colnames    `colnames<-`
set_rownames    `rownames<-`
set_names   `names<-`
set_class   `class<-`
set_attributes  `attributes<-`
set_attr    `attr<-`

Upvotes: 3

Hamzah Al-Qadasi
Hamzah Al-Qadasi

Reputation: 9786

As an addition to the answer above, it is handy to use Aliases in magrittr package, e.g.:

magrittr's pipeable operator replacements

operator functional alternative
x * y x %>% multiply_by(y)
x ^ y x %>% raise_to_power(y)
x[y] x %>% extract(y)

Upvotes: 1

jbaums
jbaums

Reputation: 27388

Surround the operators with backticks or quotes, and things should work as expected:

1:10 %>%  `*`(2) %>% sum
# [1] 110

1:10 %>%  `/`(2) %>% sum
# [1] 27.5

Upvotes: 66

Henrik
Henrik

Reputation: 67778

Or use the Aliases in magrittr package, e.g.:

1:10 %>% multiply_by(2)
# [1]  2  4  6  8 10 12 14 16 18 20

1:10 %>% add(2)
# [1]  3  4  5  6  7  8  9 10 11 12

The Aliases include 'words' for boolean operators, extract/replace, and arithmetic operators

Upvotes: 50

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