For a Shiny app: filter data based on user input. We don't know how many filtering variables will be used.

dynamic_filter.R

library(tidyverse)

# What I want
target <- mtcars %>% 
  filter(cyl %in% c(4, 8),
         gear %in% c(3, 4))
         
# Solution
dynamic_filter <- function(df, variables, conditions){ 
  filter_conditions <- purrr::map2(variables, conditions, 
                                   function(var, cond) {
                                     # Construct list of quoted filtering conditions
                                     rlang::quo(!!sym(var) %in% cond)
                                     })
  dplyr::filter(df, !!!filter_conditions)
}

var1 <- "cyl"
var2 <- "gear"

values1 <- c(4, 8)
values2 <- c(3, 4)

mtcars %>% 
  dynamic_filter(list(var1, var2), list(values1, values2)) %>% 
  identical(target)