Hi 
I am trying to develop a function for R Shiny, whose purpose is to filter the dropdowns based on a Hierarchy.
I can do it by hardcoding each reactive value and update the dropdown, where the dataframe is filtered by the above dropdowns. But I want to make a more dynamic function, since I use this kind of dropdowns alot!
I am tried to develop a function, see below, but the middle dropdown does not react to changes.
I really hope that someone is able to help me figure this out.
Many thanks,
Ricko
Minimal example below:
library(shiny)
library(dplyr)
df = data.frame(continent = c(rep("North America", 4), rep("Asia", 4), rep("Europe", 4)),
country = c(rep("USA", 2), rep("Canada", 2), rep("China", 2), rep("Vietnam", 2),
rep("France", 2), rep("Denmark", 2)),
city = c("New York", "LA", "Ontario", "Ottawa", "Beijing", "Shanghai", "Hanoi",
"Ho Chi Minh City", "Paris", "Tours", "Copenhagen", "Aarhus"))
HierarchyDependentDropdown = function(inputNames, columnNames, df, input = input, session = getDefaultReactiveDomain()){
# make the inputs into reactive values
my_reactive <- reactiveValues()
lapply(1:length(inputNames), function(i){
observe({
my_reactive[[inputNames[i]]] = input[[inputNames[i]]]
})
})
for(i in 2:length(inputNames)){
observe({
gg = lapply(1:(i-1), function(x){
if(!is.null(my_reactive[[inputNames[x]]])){
paste0(columnNames[x], " %in% c('", paste(my_reactive[[inputNames[x]]], collapse = "','"), "')")
}
})
where_str = unlist(gg)
tmp = df
if(!is.null(where_str)){
where_str = paste(where_str, collapse = " & ")
tmp = df %>% filter_(where_str)
}
tmp = tmp %>%
select(columnNames[[i]]) %>%
distinct_(columnNames[[i]]) %>%
arrange_(columnNames[[i]]) %>%
pull() %>%
as.character()
updateSelectizeInput(session,
inputId = inputNames[i],
choices = c("All" = "", tmp))
})
}
}
shinyApp(
ui = basicPage(
selectizeInput(inputId = "selectcontinent",
label = "Select Continent",
choices = c('All' = "", df %>% distinct(continent) %>% pull() %>% as.character()),
multiple = TRUE)
,selectizeInput(inputId = "selectcountry",
label = "Select Country",
choices = c('All' = "", df %>% distinct(country) %>% pull() %>% as.character()),
multiple = TRUE)
,selectizeInput(inputId = "selectcity",
label = "Select City",
choices = c('All' = "", df %>% distinct(city) %>% pull() %>% as.character()),
multiple = TRUE)
),
server = function(input, output, session) {
HierarchyDependentDropdown(inputNames = c("selectcontinent",
"selectcountry",
"selectcity"),
columnNames = c('continent',
'country',
'city'),
df = df,
input = input)
}
)