R shiny error: Problems with a reactive function

Question

I am making an interactive graph in R studio with the new shiny markdown. What the idea is to create an active page where you have two input fields to determine the size of a, the size of b and what is left is the size of c. The input is in percentage. The output is a graph with a line and bars, which works. However, I have two problems.

The second input has to be dependent of the first input, because you can never have more than 100 percent.
The size of a and b is determined after the input is given. If the input changes, a, b and c has to be determined again.

I am quite new to R and searched to other questions but could not solve my problems. This is my code and how I tried to solve it:

inputPanel(
  numericInput("aa", label = "a:",
              min = 1 , max =100 , value = 80 , step = 1),

  numericInput("bb", label = "b:",
              min = 1 , max = 100-input$aa , value = 15 , step = 1)
)

This is my first problem. I want to be the second numeric input to be reactive on the first input. I tried the following options for this problem:

  numericInput("bb", label = "b:",
              min = 1 , max = observe(100-input$aa,suspended= TRUE) , value = 15 , step = 1)

This did not work. The next thing I tried is:

  numericInput("bb", label = "b:",
              min = 1 , reactive({max = 100-input$aa}) , value = 15 , step = 1)

This as well gave an error. After trying this options, I find it quite logic it does not work, however, still can not find it how to solve this.

The second problem is in the next code.

###change the column b
 for(i in nrow(df)){reactive({
  if(input$aa>df$a[i]){
  df$b[i] = "a"
} else {if(input$aa+input$bb>df$a[i]){
  df$b[i] = "b"
}else {df$b[i] = "c"}}})}

I want to change the value of the column b in df. This piece of code does not give any errors, however, it is not active, it does not change the column b. I tried the following:

###Change the column b
shinyServer(function(input, output) {
for(i in nrow(df)){reactive({
  if(input$large>df$a[i]){
  df$b[i] = "a"
} else {if(input$aa+input$bb>df$a[i]){
  df$b[i] = "b"
}else {df$b[i] = "c"}}})}})

This seems to ignore the code even more. This is what I tried and I am quite new to R. I hope someone can help me with this issue.

Thanks in advance, EDIT After comment

Shortest program (in my opinion)

---
title: "a"
author: "b"
date: "6/24/2014"
output: html_document
runtime: shiny
---

```{r, echo=FALSE}

library(ggplot2)
library(shiny)
df= data.frame(a=c(1:20),b=c(1:20))

df$c=1 #just to make sure column c exist.
inputPanel(
  numericInput("aa", label="a", min = 1, max = 100, value =50)
              ,

  numericInput("bb",label= "b", min = 1, max = 100-input$aa, value = 10)
)

  df$c <- reactive({
  df$c <- input$aa
})

renderPlot({
  ggplot(df) +
  geom_line(aes(a, b, colour= c ))
})
```

Eddy

Please give a minimal reproducible example. It seems from what you have given thus far that you are trying to call input$x from shinyUI rather then the server. The input's can only be called from the server so you will probably need to look at using renderUI in the server to create your numericInputs. — jdharrison
– jdharrison, Commented Jun 24, 2014 at 10:08

jdharrison · Accepted Answer · 2014-06-24 11:00:15Z

3

Here is an example using renderUI. I havent looked at using shiny in markdown documents but im guessing it parses the document in a clever manner to allocate the appropriate quantities to a shinyUI and server function:

---
title: "a"
author: "b"
date: "6/24/2014"
output: html_document
runtime: shiny
---

```{r, echo=FALSE}
library(ggplot2)
library(shiny)
df= data.frame(a=c(1:20),b=c(1:20))

df$c=1 #just to make sure column c exist.
inputPanel(
  numericInput("aa", label="a", min = 1, max = 100, value = 50)
  , uiOutput('test')
)

output$test <- renderUI({
  numericInput("bb",label= "b", min = 1, max = 100-as.integer(input$aa), value = 10)
})
myReact <- reactive({
  out <- df
  out$b <- out$b + input$aa
  out
})
renderPlot({
  ggplot(myReact()) + geom_line(aes(a, b, colour= c ))
})

```

enter image description here

answered Jun 24, 2014 at 11:00

jdharrison

30.5k4 gold badges83 silver badges91 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

R shiny error: Problems with a reactive function

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related