shiny_app.R

library(lazyeval)
library(dplyr)
library(shiny)
library(ggplot2)

data(iris)
data(diamonds)

ui <- fluidPage(
      column(3,
             selectInput("data", "", choices = c('', 'iris', 'diamonds')),
             uiOutput('server_cols'),
             uiOutput("server_cols_fact"),
             uiOutput("server_params")
      ),
      column(9,
             plotOutput("plot"),
             textOutput('text')
             
      )
)

server <- function(input, output) {
      data <- reactive({
            switch(input$data, diamonds = diamonds, iris = iris)
      })
      
      output$server_cols <- renderUI({
            validate(need(input$data != "", "Firstly select a dataset."))
            data <- data()
            nam <- colnames(data)
            selectInput('cols', "Choose numeric columns:", choices = nam[sapply(data, function(x) is.numeric(x))])
      })

      output$server_cols_fact <- renderUI({
            
            req(input$data)
            
            data <- data(); nam <- colnames(data)
            selectizeInput('cols_fact', "Choose a fill columns:",
                           choices = nam[sapply(data, function(x) is.factor(x))])
      })
      
      output$server_params <- renderUI({
            
            req(input$cols_fact)
            
            data <- isolate(data()); col_nam <- input$cols_fact
            params_vec <- unique(as.character(data[[col_nam]]))
            selectizeInput('params', "Choose arguments of fill columns:", choices = params_vec,
                           selected = params_vec, multiple = TRUE)
                           
      })
      
      getDataParams <- reactive({
            
            df <- isolate(data())
            factor_col <- input$cols_fact
            col_diverse <- eval(factor_col)
            
            criteria <- interp(~col_diverse %in% input$params, col_diverse = as.name(col_diverse))
            df <- df %>%
                  filter_(criteria) %>%
                  mutate_each_(funs(factor), factor_col)
      })
      
      output$text <- renderText({
            if(!is.null(input$cols)) {
                  print(nrow(getDataParams()))
            }
      })
      output$plot <- renderPlot({
            if (!is.null(input$cols)) {

                  var <- eval(input$cols)
                  print('1')

                  diversifyData <- getDataParams()
                  factor_col <- input$cols_fact
                  print('2')

                  plot <- ggplot(diversifyData, aes_string(var, fill = diversifyData[[factor_col]])) +
                        geom_histogram(color = 'white', binwidth = 1)

                  print('3')
            }
            plot

      })

}

shinyApp(ui, server)