Create a variable number of `sliderInput` in Shiny - r

Question

My data is a matrix with a variable number of columns. Also , the range of values within the matrix is variable, too.
I want to build a variable number of sliderInput, each corresponding to one column in the matrix.
The higher limit of each slider should correspond to the maxRange within the matrix.
Any suggestion how to do it in one shot?
lapply(1:ncol, function(i) {
sliderInput(
paste0('a', i),
paste0('SelectA', i),
min = min(c(1:maxRange)),
max = max(c(1:maxRange)),
value = c(1, maxRange),
step =1
)
}
)

Answer 1

I had broadly similar problem when I wanted to create a set of input elements corresponding to values derived from the data set (min, max list of options, etc.). Broadly speaking, I would source all the required data via global.R and then reference the concepts in the elements, so on the lines of getting min/max in a slider:
global.R
# Get dates for the slider
## Delete pointless month
dta.nom$DATE_NAME <- sub("February ", replacement = "", x = dta.nom$DATE_NAME)
## Convert to number and get min/max
dta.nom$DATE_NAME <- as.numeric(x = dta.nom$DATE_NAME)
yr.min <- min(dta.nom$DATE_NAME)
yr.max <- max(dta.nom$DATE_NAME)
Then in the slider
ui.R
# Select the dates for the data
sliderInput("sliderYears", label = h5("Years"), min = yr.min,
max = yr.max, value = c(2000, 2010), sep = "",
step = 1, animate = FALSE),
Full code is on GitHub. I'm not sure if I understood you correctly but if you are interested in dynamically connecting elements of your interface in Shiny then you can make use of the updateSelectInput. Any other problems with respect to referencing the data should be solvable with use of global code and referencing the values in your interface elements.

Answer 2

In case someone might bump into the same problem, here is my solution:
ui.R
....
sidebarPanel(
selectInput(
inputId = "dataName",
label = "Select your data",
choices = c("data1", "data2", "data3", "data4")
),
uiOutput(outputId = "sliders")
),
.....
server.R
.....
output$sliders <- renderUI({
numSliders <- numCols(input$dataName)
lapply(1:numSliders, function(i) {
sliderInput(
inputId = paste0('column', i),
label = paste0('Select the range for column ', i),
min = min(selectRange(input$dataName)),
max = max(selectRange(input$dataName)),
value = c(min(selectRange(input$dataName)), max(selectRange(input$dataName))),
step =1)
})
})
........
selectRange is a another function in global.R:
global.R
selectRange <- function(x){
if(x == "data1"){choices = c(1:100)}
if(x == "data2"){choices = c(1:50)}
if(x == "data3"){choices = c(1:75)}
if(x == "data4"){choices = c(1:150)}
return(choices)
}