Interpreting the 'eruptions' variable option for knitr chunk in RMarkdown - r

I have the following knitr chunk obtained from RStudio base Rmarkdown-Shiny runtime template:
```{r eruptions, echo=FALSE}
inputPanel(
selectInput("n_breaks", label = "Number of bins:",
choices = c(10, 20, 35, 50), selected = 20),
sliderInput("bw_adjust", label = "Bandwidth adjustment:",
min = 0.2, max = 2, value = 1, step = 0.2)
)
renderPlot({
hist(faithful$eruptions, probability = TRUE, breaks = as.numeric(input$n_breaks),
xlab = "Duration (minutes)", main = "Geyser eruption duration")
dens <- density(faithful$eruptions, adjust = input$bw_adjust)
lines(dens, col = "blue")
})
```
What is the use of eruptions option in {r eruptions, echo=FALSE}

It is the name of the chunk.
You cannot give same name to different chunks.

Related

Shiny Document: how to center align output of RenderPlot

I am creating a Shiny Document in R and want the plot generated with Shiny RenderPlot to be centered, or right, or height = 50%. However, the fig.align=center or right or out-width = "50%" in the r chunk does not affect the output (I suppose it is for figures generated directly in R, not via Shiny). How to center?
Try to change out.width, or fig.align, and it won't change a thing.
--
title: "Untitled"
author: "Gahis"
date: "8/4/2021"
output: html_document
runtime: shiny
---
```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
```
```{r eruptions, echo=FALSE, fig.align='right', out.width="50%"}
inputPanel(
selectInput("n_breaks", label = "Number of bins:",
choices = c(10, 20, 35, 50), selected = 20),
sliderInput("bw_adjust", label = "Bandwidth adjustment:",
min = 0.2, max = 2, value = 1, step = 0.2)
)
renderPlot({
hist(faithful$eruptions, probability = TRUE, breaks = as.numeric(input$n_breaks),
xlab = "Duration (minutes)", main = "Geyser eruption duration")
dens <- density(faithful$eruptions, adjust = input$bw_adjust)
lines(dens, col = "blue")
})
```
Thanks!
Here is how you can reduce the width of the plot and centering it. Add this CSS:
<style>
.center50 {
margin: auto;
width: 50%;
}
</style>
Then include you renderPlot in a div with the class center50:
---
title: "Test"
output: html_document
runtime: shiny
---
<style>
.center50 {
margin: auto;
width: 50%;
}
</style>
```{r}
inputPanel(
selectInput("n_breaks", label = "Number of bins:",
choices = c(10, 20, 35, 50), selected = 20),
sliderInput("bw_adjust", label = "Bandwidth adjustment:",
min = 0.2, max = 2, value = 1, step = 0.2)
)
```
```{r}
div(class = "center50",
renderPlot({
hist(faithful$eruptions, probability = TRUE, breaks = as.numeric(input$n_breaks),
xlab = "Duration (minutes)", main = "Geyser eruption duration")
dens <- density(faithful$eruptions, adjust = input$bw_adjust)
lines(dens, col = "blue")
})
)
```

Darkly Theme RMarkdown

I am having problems setting a Darkly theme to an RMarkdown document. I am getting a light greenish background instead. Is there a solution for it? See below
---
title: "Untitled"
author:
date: "July 29, 2020"
output:
flexdashboard::flex_dashboard:
theme: darkly
runtime: shiny
---
```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
```
```{r eruptions, echo=FALSE}
inputPanel(
selectInput("n_breaks", label = "Number of bins:",
choices = c(10, 20, 35, 50), selected = 20),
sliderInput("bw_adjust", label = "Bandwidth adjustment:",
min = 0.2, max = 2, value = 1, step = 0.2)
)
renderPlot({
hist(faithful$eruptions, probability = TRUE, breaks = as.numeric(input$n_breaks),
xlab = "Duration (minutes)", main = "Geyser eruption duration")
dens <- density(faithful$eruptions, adjust = input$bw_adjust)
lines(dens, col = "blue")
})
```

Include reactive text in a R markdown shiny documents

I am a little lost and am unable to add a reactive test (te) in the shiny output of an R markdown document. A minimal example based on an R studio example is paste below.
Many thanks in advance!
Jean-Pierre
---
title: "Untitled"
runtime: shiny
output: html_document
---
```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
```
```{r eruptions, echo=FALSE}
inputPanel(
selectInput("n_breaks", label = "Number of bins:",
choices = c(10, 20, 35, 50), selected = 20),
sliderInput("bw_adjust", label = "Bandwidth adjustment:",
min = 0.2, max = 2, value = 1, step = 0.2)
)
renderText({te})
renderPlot({
startTime <- Sys.time()
# additional code goes here
endTime <- Sys.time() +1
te <- reactive(startTime - endTime)
hist(faithful$eruptions, probability = TRUE, breaks = as.numeric(input$n_breaks),
xlab = "Duration (minutes)", main = "Geyser eruption duration")
dens <- density(faithful$eruptions, adjust = input$bw_adjust)
lines(dens, col = "blue")
})
```
I think you should use te <<- reactive(startTime - endTime) to define te outside the renderPlot, use renderText({te()}) instead of renderText({te}) because it is a reactive expression, and finally put renderText({te()}) to the end after it's definition.

Reloading Rmd Html Document with Shiny Widets

I am looking at using Shiny widgets in an R-markdown file. I find this example, ran it in markdown, and then saved it as Html. However when I load it, it renders the widgets twice, and then hangs.
Is there a way I can avoid this, or is it a bug/known limitation in the system?
Here is the code:
---
runtime: shiny
output: html_document
---
### Here are two Shiny widgets
```{r echo = FALSE}
selectInput("n_breaks", label = "Number of bins:",
choices = c(10, 20, 35, 50), selected = 20)
sliderInput("bw_adjust", label = "Bandwidth adjustment:",
min = 0.2, max = 2, value = 1, step = 0.2)
```
### ...that build a histogram.
```{r echo = FALSE}
renderPlot({
hist(faithful$eruptions, probability = TRUE, breaks = as.numeric(input$n_breaks),
xlab = "Duration (minutes)", main = "Geyser eruption duration")
dens <- density(faithful$eruptions, adjust = input$bw_adjust)
lines(dens, col = "blue")
})
```
It works fine when I compile it, but when I save it and then reload it into Chrome, IE, Edge, etc... I get this:

R Shiny: multiple renderPlot calls in one R markdown document

BACKGOUND:
You can "ask" RStudio to generate an example R Markdown Shiny document, which contains this sample code:
## Inputs and Outputs
You can embed Shiny inputs and outputs in your document.
Outputs are automatically updated whenever inputs
change. This demonstrates how a standard R plot can be
made interactive by wrapping it in the Shiny
`renderPlot` function. The `selectInput` and
`sliderInput` functions create the input widgets used to
drive the plot.
```{r, echo=FALSE}
inputPanel(
selectInput("n_breaks", label = "Number of bins:",
choices = c(10, 20, 35, 50), selected = 20),
sliderInput("bw_adjust", label = "Bandwidth adjustment:",
min = 0.2, max = 2, value = 1, step = 0.2)
)
renderPlot({
hist(faithful$eruptions, probability = TRUE, breaks = as.numeric(input$n_breaks),
xlab = "Duration (minutes)", main = "Geyser eruption duration")
dens <- density(faithful$eruptions, adjust = input$bw_adjust)
lines(dens, col = "blue")
})
```
Note that this example does not make use of a folder containing ui.R and server.R.
PROBLEM:
If you copy this multiple times, the first one works as expected, and the later ones get displayed as well, but do not react to changes in the input parameters.
QUESTION:
How can you create an R Markdown document with multiple embedded plots like the above (without using external folders with ui.R and server.R), but ensuring that each one works interactively?
You must give different ids to your input elements, something like that :
First embedded shiny plot :
```{r}
inputPanel(
selectInput("n_breaks", label = "Number of bins:",
choices = c(10, 20, 35, 50), selected = 20),
sliderInput("bw_adjust", label = "Bandwidth adjustment:",
min = 0.2, max = 2, value = 1, step = 0.2)
)
renderPlot({
hist(faithful$eruptions, probability = TRUE, breaks = as.numeric(input$n_breaks),
xlab = "Duration (minutes)", main = "Geyser eruption duration")
dens <- density(faithful$eruptions, adjust = input$bw_adjust)
lines(dens, col = "blue")
})
```
Second embedded shiny plot :
```{r}
inputPanel(
selectInput("n_breaks2", label = "Number of bins:",
choices = c(10, 20, 35, 50), selected = 20),
sliderInput("bw_adjust2", label = "Bandwidth adjustment:",
min = 0.2, max = 2, value = 1, step = 0.2)
)
renderPlot({
hist(faithful$eruptions, probability = TRUE, breaks = as.numeric(input$n_breaks2),
xlab = "Duration (minutes)", main = "Geyser eruption duration")
dens <- density(faithful$eruptions, adjust = input$bw_adjust2)
lines(dens, col = "blue")
})
```
As described for example in the RStudio Shiny Tutorial, the first parameter to widget functions is the widget name, which identifies the widget. Multiple widgets with the same name will not each be usable, which is why simply creating two copies of the example does not create two working copies.
To make it work, you must make the widget names unique in each inputPanel call, and then use this names in the renderPlot calls.

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