2018-10-26
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shiny应用程序里的小工具
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More widgets这个应用程序展示的是帮助文本和提交按钮,以及用嵌入HTML元素的方式来自定义格式。要运行例子,请键入:
>
library(shiny)
>
runExample("07_widgets")
UI增强
在这个例子里,我们更新了Shiny Text程序,增加了控件,调整了格式,特别地:
- 增加了
helpText
控件,用以在输入控件旁边添加解释文本。 - 增加了
submitButton
控件,用来表示我们不想让输入和输出进行实时连接,而是想让用户点击按钮后才更新输出。这一特点在当计算过程非常复杂时是很有用的。 - 在输出面板上增加了
h4
元素(四级标题)。Shiny提供了大量的函数可直接往页面上添加HTML元素,包括标题、段落、链接等等。
下面更新后的用户接口界面的代码:
library(shiny)
# Define UI for dataset viewer application
shinyUI(pageWithSidebar(
# Application title.
headerPanel("More Widgets"),
# Sidebar with controls to select a dataset and specify the number
# of observations to view. The helpText function is also used to
# include clarifying text. Most notably, the inclusion of a
# submitButton defers the rendering of output until the user
# explicitly clicks the button (rather than doing it immediately
# when inputs change). This is useful if the computations required
# to render output are inordinately time-consuming.
sidebarPanel(
selectInput("dataset",
"Choose a dataset:",
choices
=
c("rock",
"pressure",
"cars")),
numericInput("obs",
"Number of observations to view:",
10),
helpText("Note: while the data view will show only the specified",
"number of observations, the summary will still be based",
"on the full dataset."),
submitButton("Update View")
),
# Show a summary of the dataset and an HTML table with the requested
# number of observations. Note the use of the h4 function to provide
# an additional header above each output section.
mainPanel(
h4("Summary"),
verbatimTextOutput("summary"),
h4("Observations"),
tableOutput("view")
)
))
服务端脚本
和原来的Shiny Text的程序比,所有的变化都是在用户接口界面部分,服务端脚本保持不变。
library(shiny)
library(datasets)
# Define server logic required to summarize and view the selected dataset
shinyServer(function(input,
output)
{
# Return the requested dataset
datasetInput
<-
reactive({
switch(input$dataset,
"rock"
=
rock,
"pressure"
=
pressure,
"cars"
=
cars)
})
# Generate a summary of the dataset
output$summary
<-
renderPrint({
dataset
<-
datasetInput()
summary(dataset)
})
# Show the first "n" observations
output$view
<-
renderTable({
head(datasetInput(),
n
=
input$obs)
})
})
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