R Shiny date slider animation by month (currently by day)

Question

I\'m somewhat comfortable with R, lot less with Shiny, though it\'s not my first Shiny application.

I have a data frame with lon/lat and the date/time of the entry i

Answer 1

Victorp solution works great, kudos! I'll post the code of the final solution integrated with the op. If anyone else wants to run this code, don't forget to include Victorp's sliderValues function.

library(shiny)
library(leaflet)
library(dplyr)

df <- data.frame(id = 1:5, 
             lat = c(45.53814, 45.51076, 45.4356, 45.54332, 45.52234), 
             lon = c(-73.63672, -73.61029, -73.6010, -73.56000, -73.59022),
             startDate = as.Date(c("2014-04-09", "2014-06-04", "2014-04-30", "2014-05-30", "2014-05-01")),
             year = c(2014, 2014, 2014, 2014, 2014),
             month = c(4, 6, 4, 5, 5),
             week = c(15, 23, 18, 22, 18),
             ym = as.Date(c("2014-04-01", "2014-06-01", "2014-04-01", "2014-05-01", "2014-05-01")),  # Year-Month
             yw = as.Date(c("2014-04-06", "2014-06-01", "2014-04-27", "2014-05-25", "2014-04-27"))   # Year-Week
)

# List of months
choices_month <- seq.Date(from = as.Date("2014-01-01"), by = "month", length.out = 36)

# ui
ui <- bootstrapPage(
  tags$style(type = "text/css", "html, body {width:100%;height:100%}"),

  leafletOutput("map", width = "75%", height = "100%"),

  absolutePanel(
top = 1,
right = 10,

div(
  style = "height: 180px;",
# custom slider function
sliderValues(
  inputId = "test", label = "Month", width = "100%",
  values = choices_month[4:6], 
  from = choices_month[4], to = choices_month[6],
  grid = FALSE, animate = animationOptions(interval = 1500)
), # end sliderInput
verbatimTextOutput("res")
    ) # end div
  ) # end absolutePanel
) # end bootstrapPage

server <- shinyServer(function(input, output, session){

  output$map <- renderLeaflet({
#    leaflet(data = df %>% filter(ym > as.Date(input$test[1]), ym < as.Date(input$test[2]))) %>% addTiles() %>% 
 leaflet(data = df %>% filter(ym == input$test[1])) %>% addTiles() %>% 
  addMarkers(~lon, ~lat) %>% 
  setView(lng = -73.6, lat = 45.52, zoom = 12)
  }) # end map

  output$res <- renderPrint({
    print(input$test) # you have to split manually the result by ";"
    print(as.Date(unlist(strsplit(input$test, ";"))))
    }) # end res
}) # end server

# App
shinyApp(ui = ui, server = server)