CODEWITHSUNDEEP
modelshiny
Learner_seeker
Learner_seeker

Reputation: 544

Predicting from user inputs - Shiny

I am trying to create a web interface where i want to make predictions from a pre-built model on the inputs provided by the user.

Below is the dummy data and model

# creation of dummy data and model

age=round(runif(100,15,100))
bmi=round(runif(100,15,45))
cholesterol=round(runif(100,100,200))
gender=sample(c('male','female'), 100, replace=TRUE, prob=c(0.45,0.55))
height=round(runif(100,140,200))
weight=round(runif(100,140,200))
outcome=sample(c('accepted','reject'),100,replace=T,prob=c(0.30,0.70))    
df=data.frame(age,bmi,cholesterol,gender,height,weight,outcome)
model <- glm(outcome ~.,family=binomial(link='logit'),data=df)

Now i'll have tried creating a shiny app referencing through multiple links and similar issues people have faced. I am beginner and still haven't been able to resolve the issue. While there is no error in running the app however, The output i.e. the probability is not printed anywhere on the web page

UI Code

library(shiny)
ui = fluidPage(


# this is an input object   
titlePanel("Underwriting Prediction Model"),
sidebarLayout(position = "right",
              sidebarPanel(),
              mainPanel(textOutput("Pred"))),


numericInput(inputId='age', label='Age', value = 18,min = NA, max = NA, step = NA,width = NULL),
checkboxGroupInput(inputId='gender', label='Gender', c('Male','Female'), selected = NULL, inline = FALSE,width = NULL),
numericInput(inputId='bmi', label='bmi', value = 18,min = NA, max = NA, step = NA,width = NULL),
numericInput(inputId='height', label='Height', value = 150,min = NA, max = NA, step = NA,width = NULL),
numericInput(inputId='Weight', label='Weight', value = 25, min = NA, max = NA, step = NA,width = NULL),
numericInput(inputId='cholesterol', label='Cholesterol', value = 25, min = NA, max = NA, step = NA,width = NULL),

textOutput(outputId = 'Pred')

)

Server

server = function (input,output) {
data<-reactive({
   df_final=data.frame(age=input$age,gender=input$gender,bmi=input$bmi,height=input$height,weight=input$weight,cholesterol=input$cholesterol)})

pred=reactive({predict(model,data())})

output$Pred <- renderPrint(pred())

}

shinyApp(ui=ui,server=server)

When i provide the input values, i get no printed output for my predictions. I am calling the variable in render print and the main panel yet don't see any output. What is the issue here?

Upvotes: 1

Views: 1960

Answers (2)

SeGa
SeGa

Reputation: 9809

There are several problems with your App. As @fenix_fx mentioned, you have 2 textOutput(outputId = 'Pred') which collide. So it would not render the output if one were created.

The gender input starts with a NULL value, so you have to wait in your reactive until a value was selected, otherwise it will throw an error, that the data.frame cannot be build because of different rows. You can do that with req() or validate(need(...)). I put a req(input$gender) in the data reactive.

Another problem was that you build the glm model with the gender labels male and female, but your checkboxGroupInput gives the options Male and Female. This will give you this error and the prediction cannot be made.

factor gender has new level Male

And last problem I think was that your input for weight has a capital W, while the data reactive waits for an input called input$weight with lower case w.

SIDENOTE: Your Ui seems to be arranged in a weird way. Normally you would put all inputs/outputs inside the sidebarPanel or mainPanel and not afterwards.

Resulting Code:

library(shiny)
ui = fluidPage(
  # this is an input object   
  titlePanel("Underwriting Prediction Model"),
  sidebarLayout(position = "left",
                sidebarPanel(
                  numericInput(inputId='age', label='Age', value = 18,min = NA, max = NA, step = NA,width = NULL),
                  checkboxGroupInput(inputId='gender', label='Gender', c('male','female'), selected = NULL, inline = FALSE,width = NULL),
                  numericInput(inputId='bmi', label='bmi', value = 18,min = NA, max = NA, step = NA,width = NULL),
                  numericInput(inputId='height', label='Height', value = 150,min = NA, max = NA, step = NA,width = NULL),
                  numericInput(inputId='weight', label='Weight', value = 25, min = NA, max = NA, step = NA,width = NULL),
                  numericInput(inputId='cholesterol', label='Cholesterol', value = 25, min = NA, max = NA, step = NA,width = NULL)
                ),
                mainPanel(textOutput("Pred")))
)

server = function (input,output) {
  data <- reactive({
    req(input$gender)
    data.frame(age=input$age,
               gender=input$gender,
               bmi=input$bmi,
               height=input$height,
               weight=input$weight,
               cholesterol=input$cholesterol)
    })

  pred <- reactive({
    predict(model,data())
  })

  output$Pred <- renderPrint(pred())
}

shinyApp(ui=ui,server=server)

Upvotes: 1

fenix_fx
fenix_fx

Reputation: 394

You have duplicate output 'Pred', so shiny can't do anything (in mainPanel and after all inputs in UI). Delete last and do what you need next.

Upvotes: 0

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