2018-10-26
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构建shiny应用程序之选项卡
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示例程序Tabsets展示的是如何用选项卡(tabs)来组织输出。要运行这个例子,就执行下面的命令:
> library(shiny)
> runExample("06_tabsets")
选项卡面板(Tab Panels)
选项卡(tabsets)是由调用tabsetPanel
函数创建的,在这函数中,又需要用tabPanel
函数创建选项(tab)列表。每一个选项卡面板是由输出元素组成的,这些元素在选项卡中垂直排列。
在这个例子中,我们修改了原来的Hello Shiny程序,增加了一个摘要和数据表,两者分别渲染到它们各自的选项卡中。下面就是用户接口的代码:
library(shiny)
# Define UI for random distribution application
shinyUI(pageWithSidebar(
# Application title
headerPanel("Tabsets"),
# Sidebar with controls to select the random distribution type
# and number of observations to generate. Note the use of the br()
# element to introduce extra vertical spacing
sidebarPanel(
radioButtons("dist",
"Distribution type:",
list("Normal"
=
"norm",
"Uniform"
=
"unif",
"Log-normal"
=
"lnorm",
"Exponential"
=
"exp")),
br(),
sliderInput("n",
"Number of observations:",
value
=
500,
min
=
1,
max
=
1000)
),
# Show a tabset that includes a plot, summary, and table view
# of the generated distribution
mainPanel(
tabsetPanel(
tabPanel("Plot",
plotOutput("plot")),
tabPanel("Summary",
verbatimTextOutput("summary")),
tabPanel("Table",
tableOutput("table"))
)
)
))
选项卡和反应式数据(Reactive Data)
将选项卡引入用户接口的时候,应该强调为共享数据创建反应表达式的重要性。在这个例子中,每个选项卡都提供了对数据集的查看方式。如果对数据集的处理比较费时,那么用户接口的定义可能变得很慢。下面的服务端脚本展示的是如何用反应表达式一次性计算数据,其结果被三个选项卡所共享。
library(shiny)
# Define server logic for random distribution application
shinyServer(function(input,
output)
{
# Reactive expression to generate the requested distribution. This is
# called whenever the inputs change. The renderers defined
# below then all use the value computed from this expression
data
<-
reactive({
dist
<-
switch(input$dist,
norm
=
rnorm,
unif
=
runif,
lnorm
=
rlnorm,
exp
=
rexp,
rnorm)
dist(input$n)
})
# Generate a plot of the data. Also uses the inputs to build the
# plot label. Note that the dependencies on both the inputs and
# the 'data' reactive expression are both tracked, and all expressions
# are called in the sequence implied by the dependency graph
output$plot
<-
renderPlot({
dist
<-
input$dist
n
<-
input$n
hist(data(),
main=paste('r',
dist,
'(',
n,
')',
sep=''))
})
# Generate a summary of the data
output$summary
<-
renderPrint({
summary(data())
})
# Generate an HTML table view of the data
output$table
<-
renderTable({
data.frame(x=data())
})
})
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