rlang

Sometimes when working with dplyr one has a character vector of column names that's to be used to operate on data, for instance: cols_of_interest <- c("Petal.Width", "Petal.Length") In dplyr 0.5.0 and earlier, the recommended approach to this problem was to use the verb_ underscore construct as follows: library("tidyverse") my_cols <- c("Petal.Width", "Petal.Length") iris %>% select_(.dots = my_cols) The verb_ functions are now deprecated in favour of the new tidy evaluation framework (dplyr.tidyverse.org/articles/programming.html) introduced by the rlang library. As of dplyr 0.7.0 the

I'd like to use dplyr's programming magic , new to version 0.7.0, to coalesce two columns together. Below, I've listed out a few of my attempts. df <- data_frame(x = c(1, 2, NA), y = c(2, NA, 3)) # What I want to do: mutate(df, y = coalesce(x, y)) # Here's the expected output: #> # A tibble: 3 x 2 #> x y #> <dbl> <dbl> #> 1 1 1 #> 2 2 2 #> 3 NA 3 I thought fn1 would work, but it's treating varname as character on the right-hand side. fn1 <- function(varname) { mutate(df, UQ(varname) := coalesce(x, !!varname)) } fn1("y") # Error in mutate_impl(.data, dots) : # Evaluation error: Argument 2 must

I want to apply different functions to the same column in a tibble. These functions are stored in a character string. I used to do this with mutate_ and the .dots argument like this: library(dplyr) myfuns <- c(f1 = "a^2", f2 = "exp(a)", f3 = "sqrt(a)") tibble(a = 1:3) %>% mutate_(.dots = myfuns) This approach still works fine but mutate_ is deprecated. I tried to achieve the same result with mutate and the rlang package but did not get very far. In my real example myfuns contains about 200 functions so typing them one by one is not an option. Thanks in advance. Convert your strings to

I recently notices that rlang::sym doesn't seem to work in anonymous functions and I don't understand why. Here an example, it's pretty clumsy and ugly but I think it illustrates the point require(tidyverse) data <- tibble(x1 = letters[1:3], x2 = letters[4:6], val = 1:3) get_it <- function(a, b){ data %>% mutate(y1 = !!rlang::sym(a)) %>% mutate(y2 = !!rlang::sym(b)) %>% select(y1, y2, val) } get_it("x1", "x2") This defines some toy data and a (horrible) function that essentially renames the columns based on column names. Now I can do the same thing for different combinations of a and b: d <-

Define an expression > xy <- expr(x+y) Use it to build a second expression ... and it works > expr(a + !!xy) a + (x + y) simply changing the order of the arguments and it stops working > expr(!!xy + a) Error in (function (x) : object 'a' not found Am I missing something? Thanks There is way to make it work. Change the way !!xy has been used in expr and it will work. i.e expr((!!xy) + a) #(x + y) + a The reason is that priority of all arithmetic and comparison operators are higher than ! . Hence arithmetic and comparison operators binds tightly than ! . e.g.: > expr(!!2 + 3) [1] 5 > expr((!!2)

I am writing my function and want to use dplyr's filter() function to select rows of my data frame that satisfy a condition. This is my code: library(tidyverse) df <-data.frame(x = sample(1:100, 50), y = rnorm(50), z = sample(1:100,50), w = sample(1:100, 50), p = sample(1:100,50)) new <- function(ang,brad,drau){ df%>%filter(!!drau %in% 1:50)%>%select(ang,brad) -> A return(A) } brand <- c("z","w","p") lapply(1:3, function(i) new(ang = "x", brad = "y", drau = brand[i]))%>%bind_rows() Anytime I run this function, it looks like filter doesn't select any rows that satisfy the condition. How can I

I am trying to use the following function but every time I do, I receive the error below. I tried installing an older version of rlang as it works on a different R Studio but I was unable to do that. It seems the error is due to the 0.3.0 version. Any suggestions on how to fix this error would be appreciated. details2 <- details %>% mutate(rownames=rownames(.)) %>% filter(isdir==FALSE) %>% arrange(desc(ctime)) Error in mutate_impl(.data, dots) : Evaluation error: `as_dictionary()` is defunct as of rlang 0.3.0. Please use `as_data_pronoun()` instead. To solve this issue within a docker