我正在使用Shiny和R交互地可视化我的数据。我想在Iris数据集中绘制Petal.Width与Petal.Length的交互式散点图,并基于k个聚类(用户输入)和p(专用于训练数据集的数据行的百分比)(用户输入)对点进行聚类。我在散点图上添加了悬停功能,以便通过单击每个点,可以演示该点的整个数据集。
# Loading Libraries
library(shiny)
library(caret)
library(ggplot2)
data(iris)
ui <- pageWithSidebar(
headerPanel("Clustering iris Data"),
sidebarPanel(
sliderInput("k", "Number of clusters:",
min = 1, max = 5, value = 3),
sliderInput("prob", "Training percentage:",
min=0.5, max=0.9, value = 0.7)),
mainPanel(
# img(src='iris_types.jpg', align = "center", height="50%", width="50%"),
plotOutput("plot1", click = "plot_click"),
verbatimTextOutput("info")
)
)
server <- function(input, output) {
inTrain <- createDataPartition(y=iris$Species,
p=input$prob,
list=FALSE)
training <- iris[ inTrain,]
testing <- iris[-inTrain,]
kMeans1 <- kmeans(subset(training,
select=-c(Species)),
centers=input$k)
training$clusters <- as.factor(kMeans1$cluster)
output$plot1 <- renderPlot({
qplot(Petal.Width,
Petal.Length,
colour = clusters,
data = training,
xlab="Petal Width",
ylab="Petal Length")
})
output$info <- renderPrint({
# With ggplot2, no need to tell it what the x and y variables are.
# threshold: set max distance, in pixels
# maxpoints: maximum number of rows to return
# addDist: add column with distance, in pixels
nearPoints(iris, input$plot_click, threshold = 10, maxpoints = 1,
addDist = FALSE)
})
}
shinyApp(ui, server)
在R Studio中运行应用程序时,出现以下错误:
Error in .getReactiveEnvironment()$currentContext() :
Operation not allowed without an active reactive context. (You tried to do something that can only be done from inside a reactive expression or observer.)
答案 0 :(得分:1)
如@Clemsang所述,您在oberserver/render*
函数外部使用电抗值。
您想要做的是创建一个reactive
环境,您可以在其中使用输入。也就是说,每当输入更改时,都会重新计算某些内容。因此,您需要将训练计算包装在reactive
中,并且要在渲染函数中使用它时,可以通过添加()
来“调用”它。我喜欢用动词来命名我的反应堆,以强调这样一个事实,即我在调用这些函数时实际上在做某事,因此命名为get_training_data
:
server <- function(input, output) {
get_training_data <- reactive({ ## now your inputs are in a reactive environment
inTrain <- createDataPartition(y=iris$Species,
p=input$prob,
list=FALSE)
training <- iris[ inTrain,]
testing <- iris[-inTrain,]
kMeans1 <- kmeans(subset(training,
select=-c(Species)),
centers=input$k)
training$clusters <- as.factor(kMeans1$cluster)
training
})
output$plot1 <- renderPlot({
qplot(Petal.Width,
Petal.Length,
colour = clusters,
data = get_training_data(),
xlab="Petal Width",
ylab="Petal Length")
})
output$info <- renderPrint({
# With ggplot2, no need to tell it what the x and y variables are.
# threshold: set max distance, in pixels
# maxpoints: maximum number of rows to return
# addDist: add column with distance, in pixels
nearPoints(iris, input$plot_click, threshold = 10, maxpoints = 1,
addDist = FALSE)
})
}