如何从R Shiny selectInput()的列表中提取元素名称而不是值? [英] How to extract element name, not value, from a list in R Shiny selectInput()?
问题描述
我想从R Shiny的selectInput()中用于choices自变量的列表中提取元素名称，而不是特定值.
I would like to extract the element name, and not the specific value, from a list used for the choices argument in selectInput() from R Shiny.
selectInput函数如下所示:
# ...
selectInput("xvar", "What is the predictor variable?",
choices = list("MPG" = "mpg",
"Cylinders" = "cyl",
"Engine Displacement" = "disp",
"Horse Power" = "hp",
"Gears" = "gear"),
# ...
在我的server.R代码中，我想使用例如汽缸"而不是"cyl"作为轴标签.例如(使用ggplot2):
In my server.R code I would like to use, for example, "Cylinders" and not "cyl" as an axis label. For example (using ggplot2):
# ...
labs(x = input$xvar, y = input$yvar) +
# ...
names(input$xvar)返回NULL.有什么方法可以调用input$xvar并返回名称吗?
names(input$xvar) returns NULL. Is there any way to call input$xvar and return the name?
推荐答案
Thanks to Paul's comments, the links he provided, and this SO thread, I was able to answer my question.
下面，我提供了旧的ui.R和server.R脚本，这些脚本生成了我不满意的轴标签，以及新的ui.R和server.R脚本，其中的轴标签得到了改进. (新脚本中的更改用# diff标记)
Below I provide the old ui.R and server.R scripts which generated axis labels I was not happy with, as well as new ui.R and server.R scripts where the axis labels are improved. (Changes in the new scripts are marked with # diff)
旧的ui.R:
shinyUI(fluidPage(
titlePanel("Fit Regression Line for Chosen Variables and Points"),
sidebarLayout(
sidebarPanel(
h2("Model Specifics"), br(),
selectInput("xvar", "What is the predictor variable?",
choices = list("MPG" = "mpg",
"Cylinders" = "cyl",
"Engine Displacement" = "disp",
"Horse Power" = "hp",
"Gears" = "gear"),
multiple = FALSE),
selectInput("yvar", "What is the outcome variable?",
choices = list("MPG" = "mpg",
"Cylinders" = "cyl",
"Engine Displacement" = "disp",
"Horse Power" = "hp",
"Gears" = "gear"),
multiple = FALSE, selected = "cyl"),
h4("Intercept"), textOutput("int"),
h4("Slope"), textOutput("slope")
),
mainPanel(
br(), h2("Display"), h4("Drag to select which points to include in model"),
plotOutput("plot", brush = brushOpts(id = "brush1"))
)
)
))
旧的server.R:
shinyServer(function(input, output) {
model <- reactive({
points <- brushedPoints(mtcars, brush = input$brush1,
xvar = input$xvar,
yvar = input$yvar)
if(nrow(points) <= 1) {
return(NULL)
} else {
lm(as.formula(paste0(input$yvar,
"~", input$xvar)),
data = points)
}
})
output$int <- renderText({
if(is.null(model())) {
"Too few data points selected"
} else {
round(model()[[1]][1], 2)
}
})
output$slope <- renderText({
if(is.null(model())) {
"Too few data points selected"
} else {
round(model()[[1]][2], 2)
}
})
output$plot <- renderPlot({
library(ggplot2)
ggplot(mapping = aes(x = mtcars[, input$xvar],
y = mtcars[, input$yvar])) +
theme_minimal() +
geom_point() +
labs(x = input$xvar, y = input$yvar) +
coord_cartesian(x = c(0, 1.2*max(mtcars[, input$xvar])),
y = c(0, 1.2*max(mtcars[, input$yvar]))) +
if(!is.null(model())) {
geom_abline(intercept = model()[[1]][1], slope = model()[[1]][2],
colour = "red", lwd = 2, alpha = 0.3)
}
})
})
脚本中的更改用# diff
新的ui.R:
shinyUI(fluidPage(
titlePanel("Fit Regression Line for Chosen Variables and Points"),
sidebarLayout(
sidebarPanel(
h2("Model Specifics"), br(),
uiOutput("si_xvar"), # diff
uiOutput("si_yvar"), # diff
h4("Intercept"), textOutput("int"),
h4("Slope"), textOutput("slope")
),
mainPanel(
br(), h2("Display"), h4("Drag to select which points to include in model"),
plotOutput("plot", brush = brushOpts(id = "brush1"))
)
)
))
新的server.R:
shinyServer(function(input, output) {
varlist <- list("MPG" = "mpg", # diff
"Cylinders" = "cyl",
"Engine Displacement" = "disp",
"Horse Power" = "hp",
"Gears" = "gear")
output$si_xvar <- renderUI( # diff
selectInput("xvar", "What is the predictor variable?",
choices = varlist,
multiple = FALSE)
)
output$si_yvar <- renderUI( # diff
selectInput("yvar", "What is the outcome variable?",
choices = varlist,
multiple = FALSE, selected = "cyl")
)
model <- reactive({
points <- brushedPoints(mtcars, brush = input$brush1,
xvar = input$xvar,
yvar = input$yvar)
if(nrow(points) <= 1) {
return(NULL)
} else {
lm(as.formula(paste0(input$yvar,
"~", input$xvar)),
data = points)
}
})
output$int <- renderText({
if(is.null(model())) {
"Too few data points selected"
} else {
round(model()[[1]][1], 2)
}
})
output$slope <- renderText({
if(is.null(model())) {
"Too few data points selected"
} else {
round(model()[[1]][2], 2)
}
})
output$plot <- renderPlot({
library(ggplot2)
ggplot(mapping = aes(x = mtcars[, input$xvar],
y = mtcars[, input$yvar])) +
theme_minimal() +
geom_point() +
labs(x = names(which(input$xvar == varlist)), # diff
y = names(which(input$yvar == varlist))) + # diff
coord_cartesian(x = c(0, 1.2*max(mtcars[, input$xvar])),
y = c(0, 1.2*max(mtcars[, input$yvar]))) +
if(!is.null(model())) {
geom_abline(intercept = model()[[1]][1], slope = model()[[1]][2],
colour = "red", lwd = 2, alpha = 0.3)
}
})
})
这篇关于如何从R Shiny selectInput()的列表中提取元素名称而不是值?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
