Questions tagged [quasiquotes]
70 questions
3
votes
2 answers
Named vector "by" arguments for `dplyr::_join` functions
I am writing a function to dplyr::_join two dataframes by different columns, with the column name of the first dataframe dynamically specified as a function argument. I believe I need to use rlang quasiquotation/metaprogramming but haven't been able…
maia-sh
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3
votes
1 answer
Only strings can be converted to symbols within a function in R
I have a function that is intended to operate on data obtained from a variety of sources with many manual entry fields. Since I don't know what to expect for the layout or naming convention used in these files, I want it to 'scan' a data frame for…
SGE
- 311
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- 10
3
votes
3 answers
Why is plotly() and enquo + !! in conflict?
I am writing a function that uses plot_ly for a pieplot. The tilde (~) within argument labels = ~ is in conflict with the unquote operator !!. Is there a solution for this problem?
pieplotr <- function (df, Property){
Property_Name <-…
Soph Carr
- 31
- 5
3
votes
1 answer
Haskell analog of lisp backquoting and splicing
In some lisps (e.g. elisp, common lisp) there is a feature called backquoting.
It allows to construct a list while evaluating or splicing into it some elements. For example:
`(1 2 (3 (+ 4 5)))
⇒ (1 2 (3 (+ 4 5))) ; just quoted unevaluated…
grepcake
- 3,960
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- 26
3
votes
1 answer
How can I write a pattern quasi quoter in Haskell?
I use quasi quoters to create my smart-constructed data types at compile time. This looks something like:
import qualified Data.Text as T
import Language.Haskell.TH.Quote (QuasiQuoter(..))
import Language.Haskell.TH (Q, Exp, Pat(..), Lit(..))
import…
MaxGabriel
- 7,617
- 4
- 35
- 82
3
votes
1 answer
Using a quasiquoted argument to a function within a purrr:map call
I'm having a little trouble figuring out quasiquotation, specifically I have a function which takes an argument which specifies which variable should go into a model which is then run within a purrr::map call.
I've been working from:…
Richard J. Acton
- 885
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- 17
3
votes
2 answers
Using rlang::sym inside list definition
I'm writing an R script and I need to allow user to specify the name of variable that will be proccessed by hand, i.e.
var <- 'user_name'
Generally then I refer to that using rlang::sym and quoting/unquoting mechanism. However, I need to use…
jakes
- 1,964
- 3
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- 50
3
votes
2 answers
Haskell QuasiQuotes Text.RawString.QQ interpolation
How can I interpolate like this:
{-# LANGUAGE QuasiQuotes #-}
import Text.RawString.QQ
myText :: Text -> Text
myText myVariable = [r|line one
line two
line tree
${ myVariable }
line five|]
myText' :: Text
myText' = myText "line four"
${…
FtheBuilder
- 1,410
- 12
- 19
3
votes
0 answers
Non linear patterns in quasi-quotes
I followed this tutorial to implement a quasi quoted DSL, and I now want to support non-linear patterns in a quoted pattern. That will allow a repeated binder in a pattern to assert the equality of the matched data. For example, one can then write…
rem
- 893
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- 18
2
votes
1 answer
How to pass more than one environmental variable name to `by` parameter in dplyr `join` functions?
Let's say I'm writing a wrapper function for full_join (but the question applies to left_join, right_join, and inner_join). The join variables need to be specified by the user in the function call and the function needs to allow for situations when…
ESELIA
- 132
- 1
- 12
2
votes
1 answer
Is it legal to modify a list created using quasiquote?
From my understanding, it is not legal to modify a list created using quote:
(let ((numbers '(3 2 1)))
(set-car! numbers 99) ; Illegal.
numbers)
What about lists created using quasiquote? Is it legal to modify lists created using…
Flux
- 9,805
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- 46
- 92
2
votes
2 answers
default arguments not being recognized in custom function using dplyr
Take this function foo(). I want it to have a default argument of cyl because that's the name of the field it will usually process.
library(tidyverse)
foo <- function(x = cyl){
case_when(
x == 6 ~ TRUE,
x == 8 ~ FALSE,
x…
Joe
- 3,217
- 3
- 21
- 37
2
votes
1 answer
Unquoting argument inside of function in R
I cannot figure out why the bang-bang operator in my function is not unquoting my grp argument. Any help would be much appreciated!
library(dplyr)
test_func <- function(dat, grp){
dat %>%
group_by(!!grp) %>%
summarise(N = …
Jordan Hackett
- 689
- 3
- 11
2
votes
2 answers
Pass string as argument to paste function
I'm trying to pass string variable names to the paste function to paste all strings together. Here's a mwe:
#bind strings to variable names
a <- c("abc", "def", "ghi")
b <- c("jkl", "mno", "pqr")
c <- c("stu", "vwx",…
Tea Tree
- 882
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- 26
2
votes
2 answers
Using `expr()` inside the function
The Chapter 19 of Advanced R explains that expr() is not useful inside the function.
However, in the following case, I could not make a function work without expr().
Let's suppose I want to group a tibble in a function.
data(iris)
iris %>%…
user51966
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