Shiny - Taking Text input into auxiliary function - r

I am new to Shiny and trying to build a more accessible input and output for a function I built. I am giving this to people that don't run R so trying to build something that runs my functions in the background and then spits out the answer.
I am having some trouble getting everything in the way that I want it unfortunately and dealing with a bunch of errors. However, here is my more pointed question:
The actual function that I want to run takes a name (in quotations as "Last,First") and a number.
PredH("Last,First",650)
So I want a shiny application that takes a name input and a number input that then runs this program and then spits back out a data table with my answer. So a couple of questions.
How do I get it in the right form to input into my equation on the server side script, do I need to return it in the function so it can be accessed using a function$table type access? (Right now I am just printing using cat() function in the console for the function but know that may not be usable for this type of application.
I want to return a dataframe that can be gotten at PredH14$table. How do I go about building that shiny?
Here is my code so far:
UI:
library(shiny)
shinyUI(pageWithSidebar(
# Application title
headerPanel("Miles Per Gallon"),
# Sidebar with controls to select the variable to plot against mpg
# and to specify whether outliers should be included
sidebarPanel(
textInput("playername", "Player Name (Last,First):", "Patch,Trevor"),
radioButtons("type", "Type:",
list("Pitcher" = "P",
"Hitter" = "H"
)),
numericInput("PAIP", "PA/IP:", 550),
submitButton("Run Comparables")
),
mainPanel(
textOutput("name")
)
Server:
library(shiny)
shinyServer(function(input, output) {
sliderValues <- reactive({
data.frame(
Name = c("name", "PA"),
Value = c(as.character(playername),
PAIP),
stringsAsFactors=FALSE)
})
name=input[1,2]
PAIP=input[2,2]
testing <- function(name,PAIP){
a=paste(name,PAIP)
return(a) }
output$name=renderText(testing$a)
})

I am not quite sure I understood your question 100% but I clearly see you are wondering how to pass the input of the UI into the server and maybe, the other way back.
In your server code, clearly you are not getting any input from the UI. Basically you have created three input variables in your ui.R:
1. input$playername
2. input$type
3. input$PAIP
And one output:
1. output$name
Just let you know, the function sliderValues <- reactive(..) is called every time there is any input from the input... like people click the dropdown list or people modifies words in the text box.
You can even get started without the submit button just to get started. But the existence of the submit button actually makes everything easier. Create a submit button for an input form. Forms that include a submit button do not automatically update their outputs when inputs change, rather they wait until the user explicitly clicks the submit button.
So you can put your code in a way similar like this:
# server.R
library(shiny)
shinyServer(function(input, output) {
sliderValues <- reactive({
result <- ... input$playername ... input$type ... input$PAIP
return(result)
})
output$name <- renderPlot/renderText (... sliderValues...)
})
# ui.R
library(shiny)
shinyUI(pageWithSidebar(
headerPanel("Miles Per Gallon"),
sidebarPanel(
textInput("playername" ... ),
radioButtons("type" ... ),
numericInput("PAIP" ... ),
submitButton("...")
),
mainPanel(
textOutput/plotOutput...("name")
)
))
In the end, check out the shiny example that might be what you want.
library(shiny)
runExample('07_widgets')

Related

[RShiny][Shinydashboard]Show/Hide different input panel based on another input

I have built shiny App before, but I am getting rusty after not writing the code for a while.
Here is my goal:
I am designing a dynamic UI using shinydashboard. I have one selectInput (e.g., A, B, C and D).
What I want to make the app perform is that, based on the user option (either A, B, C or D), it will dynamically pop up another input panel (a panel with specific collection of "numericInput"s or "selectInput"s), as each A/B/C/D option defines different situation.
I could not provide my own code (as I do not have any idea on even how to get started), but I find some page with example code here:
An example of dynamic UI
It is the example in section 10.2.1 of the page using tabsetPanel and updateTabsetPanel.
I checked their app link and it seems to be exactly what I want, but I suspect that some of the code has been depleted by Shiny already as when I copy and paste the code to my R script, I could not run it without error.
If you could kindly help, either on how to properly adjust the code on that page, or if there is any other approach, it will be greatly appreciated.
Easiest way would be using uiOutput and renderUI.
library(shiny)
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
selectInput("controller", "Show", choices = c("A", "B", "C", "D")),
uiOutput("newSelect")
),
mainPanel(
textOutput("textId")
)
)
)
server <- function(input, output, session) {
output$textId <- renderText({
input$controller
})
output$newSelect <- renderUI({
if(input$controller == "B"){
selectInput("controller2", "New Select", choices = c(1:4))
} else {
NULL
}
})
}
shinyApp(ui,server)
Bare in mind this can make your app laggish if it gets too complex. If so, you can use some js to show or hide the other selectInputs conditionally

In Shiny, the submit button isn't running

I wrote a R script (MAIN.R) that converts PDF tables to CSV. When I run MAIN.R as an individual file, it functions well. I've tried it many times.
Currently, I'm working on a R shiny app that uses "MAIN.R" as a source and takes a pdf file as input. When I push the submit button, the output should appear in the MAIN panel. Unfortunately, the submit button does not function as intended.
May anyone please assist me with this, as I am new to Shiny?
UI.R
shinyUI(fluidPage(
titlePanel("DATASET CONVERSION"),
sidebarLayout(
fileInput("filein", label = h2("Select a file to convert.")),
submitButton("Submit")
),
mainPanel(
tableOutput("Dataset")
)
)
)
Server.R
source("MAIN.R")
shinyServer(function(input, output) {
outputdf <- reactive({ input$filein
})
output$Dataset <- renderTable({
outputdf()
})
})
Your Submit button is not currently linked to anything, so it will not do anything. If I am reading the code right, you are just taking the input dataset and storing it as the output of outputdf. Your output$Dataset then just picks up that outputdf and displays it as-is, without any work being done on it.
You use an action button like so:
## In UI.R
actionButton("execute", "Execute the Main Function")
## In Server.R
observeEvent(input$execute, {
## Do stuff here
})
Note that the actionButton has two parameters, inputID (which is how you refer to it) and text to display on top. For example, with input$filein, 'filein' is the inputID.
In Server.R, observeEvent won't do anything until it detects a change in input$execute, which happens when someone clicks the button. That is where you put your code to do stuff.
Now, in output$Dataset, you need to access the results of whatever you did in that observeEvent. One way to do that is to use a reactiveValue. This is just like a reactive, but instead of a function, it stores a data element. Initialize it as an empty dataframe, and then update it in the observeEvent. Something like this:
## In Server.R
treated_output <- reactiveValue(data.frame())
observeEvent(input$execute, {
## Run the function on the file
updated <- main_function(input$filein)
# Update your reactiveValue
treated_output(updated)
})
output$Dataset <- renderTable({
treated_output()
})
Does this make sense?

R Shiny : Refreshing plot when entering input OR pressing an action button

I'm fairly new to R Shiny but am stuck with the following problem for some time now and hope you can provide some help:
I try to refresh a plot in R shiny that should be refreshed if either a new input argument is entered OR an action button is pressed. This should be straightforward, but unfortunately I can't solve it, despite googling/reading instructions for some time. Any advice would be recommended. Any solutions on the web seem to put the whole renderplot function inside the observeEvent function, but I also need the renderplot in addition outside of it to account for the possibility of just entering inputs without pressing the action button.
I have no trouble creating a (render)plot that either exclusively is refreshed when entering a new input or exclusively refreshed when pressing a button.
However when doing both at the same I fail: I first tried to copy the renderplot function including the resulting output twice one time within an observeEvent function (to account for clicking the action button) and one time outside of an observeEvent (to account for only refreshing the inputs to the plot) but this leads only to a greyed out graph that refreshes after ~10 seconds delay when pressing the action button. I imagine adding the reactive click input generated from clicking the action button directly to the renderplot outside of observe event , but so far I couldn't get it to run. Any recommendations would be much appreciated.
Thank you in advance.
Like this?:
Edit: No need to pass the selectInput to the reactive Vals.. this does the same:
library(shiny)
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
selectInput(inputId="select", label="title", choices=LETTERS[1:3], selected = "A"),
actionButton(inputId="btn", label="refresh")
),
mainPanel(
plotOutput("scatterPlot")
)
)
)
server <- function(input, output) {
plotSettings <- reactiveValues()
observeEvent(c(input$btn, input$select), {
plotSettings$values <- runif(100,1,100)
# plotSettings$title <- input$select
}, ignoreNULL = FALSE)
output$scatterPlot <- renderPlot({
plot(plotSettings$values, main=input$select)
})
}
shinyApp(ui = ui, server = server)

R Shiny accessing a dynamic input

I am new to shiny, I have been stuck on this for quite a while and the things I tried and read so far held no fruits. I have a dropdown, where the user will choose a Question, then depending on the question, a drop down will be populated with the response numbers. After the user chooses the response number a map will be plotted. I have gone through the dynamic drop down list, that is done. But I cannot get access to the second user input, the response number, so I can select my data for the map accordingly. I feel like this is really simple I don't know why this does not work. I am getting this error:
Error in .getReactiveEnvironment()$currentContext() : Operation not
allowed without an active reactive context. (You tried to do something
that can only be done from inside a reactive expression or observer.)
My code is as follows, I have tentatively put in special cases and later I will expand to a general case with lists.
library(shiny)
runApp(list(
ui = shinyUI(pageWithSidebar(
headerPanel('Dialect Comparison'),
sidebarPanel(
selectInput('Question', 'Choose The Question', c('100. Do you cut or mow the lawn or grass?'='Q100',
'101. Do you pass in homework or hand in homework?'='Q101')),
uiOutput('C')
),
mainPanel(
plotOutput('plot')
)
)
),
server = function(input, output){
output$C = renderUI({
ques = input$Question
selectInput('Choice', 'Choose The Response', seq(0,max(ling_data[,ques])))
})
##########
#The Data#
##########
#text = renderPrint({'uhu'})
#print(text()) #THIS WORKS
choice_number = renderPrint({input$Choice}) #http://shiny.rstudio.com/gallery/dynamic-ui.html
print(choice_number()) #it fails here
...
})
}
))
Reactive variables, including inputs, can be accessed only in a reactive scope created using one of the following:
shiny::reactive, shiny::eventReactive
shiny::observe, shiny::observeEvent
shiny::render*
or inside shiny::isolate block.
For actions like logging you probably want observe block:
observe({print(choice_number())})

Can I save the old value of a reactive object when it changes?

Note: After coming up with the answer I reworded the question to make if clearer.
Sometimes in a shiny app. I want to make use of a value selected by the user for a widget, as well as the previous value selected for that same widget. This could apply to reactive values derived from user input, where I want the old and the new value.
The problem is that if I try to save the value of a widget, then the variable containing that value has to be reactive or it will not update every time the widget changes. But, if I save the the value in a reactive context it will always give me the current value, not the previous one.
How can I save the previous value of a widget, but still have it update every time the user changes the widget?
Is there a way that does not require the use of an actionButton every time the user changes things? Avoiding an actionButton can be desirable with adding one is otherwise unnecessary and creates excess clicking for the user.
Seeing as the session flush event method seems to be broken for this purpose, here is an alternative way to do it using an observeEvent construct and a reactive variable.
library(shiny)
ui <- fluidPage(
h1("Memory"),
sidebarLayout(
sidebarPanel(
numericInput("val", "Next Value", 10)
),
mainPanel(
verbatimTextOutput("curval"),
verbatimTextOutput("lstval")
)
)
)
server <- function(input,output,session) {
rv <- reactiveValues(lstval=0,curval=0)
observeEvent(input$val, {rv$lstval <- rv$curval; rv$curval <- input$val})
curre <- reactive({req(input$val); input$val; rv$curval})
lstre <- reactive({req(input$val); input$val; rv$lstval})
output$curval <- renderPrint({sprintf("cur:%d",curre())})
output$lstval <- renderPrint({sprintf("lst:%d",lstre())})
}
options(shiny.reactlog = TRUE)
shinyApp(ui, server)
Yielding:
Update This answer was posted before the advent of the reactiveValues/observeEvent model in shiny. I think that #MikeWise 's answer is the better way to do this.
After some playing around this is what I came up with. The ui.r is nothing special
ui.r
library(shiny)
ui <- shinyUI(fluidPage(
sidebarLayout(
sidebarPanel(
selectizeInput(inputId="XX", label="Choose a letter",choices=letters[1:5])
),
mainPanel(
textOutput("Current"),
textOutput("old")
)
)
))
"Current" will display the current selection and "old" displays the previous selection.
In the server.r I made use of three key functions: reactiveValues, isolate and session$onFlush.
server.r
library(shiny)
server <- function(input, output,session) {
Values<-reactiveValues(old="Start")
session$onFlush(once=FALSE, function(){
isolate({ Values$old<-input$XX })
})
output$Current <- renderText({paste("Current:",input$XX)})
output$old <- renderText({ paste("Old:",Values$old) })
}
The server.r works like this.
First, Values$old is created using the reactiveValues function. I gave it the value "Start" to make it clear what was happening on load up.
Then I added a session$onFlush function. Note that I have session as an argument in my server function. This will run every time that shiny flushes the reactive system - such as when the selectizeInput is changed by the user. What is important is that it will run before input$XX gets a new value - so the value has changed at the selectizeInput but not at XX.
Inside the session$onFlush I then assign the outgoing value of XX to Values$old. This is done inside an isolate() as this will prevent any problems with input$XX gets updated with the new values. I can then use input$XX and Values$old in the renderText() functions.

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