Loading online xml data to slider in R shiny dashboard - r

Question

My friend and I built an R shiny dashboard using downloaded data. The code is as follows:
library(shiny)
library(shinydashboard)
library(dplyr)
library(tidyverse)
library(reshape)
library(scales)
ecd <- read.csv("ecd-figures.csv")
c(
"No of case" = "no_of_case",
"Minor Case" = "minor_case",
"All Non Fatal Case" = "all_non_fatal_case",
"Fatal Case" = "fatal_case"
) -> vec
ui <- fluidPage(sidebarLayout(
sidebarPanel
(
checkboxGroupInput("feature",
"Feature",
vec),
sliderInput(
"year",
"Year",
min = min(ecd$year),
max = max(ecd$year),
value = range(ecd$year),
sep = "",
step = 1
)
),
mainPanel(tabsetPanel(
tabPanel("Plot", plotOutput("correlation_plot")),
tabPanel("Table", tableOutput("ecd"))
))
))
server <- function(input, output) {
yearrange <- reactive({
ecd %>%
subset(year %in% input$year[1]:input$year[2]) %>%
select(c(year, input$feature))
})
output$correlation_plot <- renderPlot({
ecdsubset <- yearrange()
ecdsubset <- melt(ecdsubset, id = "year")
validate(need(input$feature, 'Check at least one item.'))
ggplot(ecdsubset, aes(x = year, y = value, color = variable)) + geom_line(size = 1) + scale_x_continuous(breaks =
seq(input$year[1], input$year[2], by = 1))
})
output$ecd <- renderTable({
yearrange()
})
}
shinyApp(ui, server)
The simple data file is here: https://drive.google.com/file/d/1pZQe89wxw14lirW2mRIgi9h29yPyc7Fs/view?usp=sharing
Then, I want to make everything online, i.e. calling api and not to download the csv file. It seems ok to read the contents rather simply, as follows:
library(xml2)
ecd_xml <-"https://www.labour.gov.hk/datagovhk/resource/ecd/ecd-figures.xml"
read_ecd <- read_xml(ecd_xml)
xml_find_all(read_ecd, ".//year")
{xml_nodeset (5)}
[1] <year>2015</year>
[2] <year>2016</year>
[3] <year>2017</year>
[4] <year>2018</year>
[5] <year>2019</year>
The problem is: how to parse every piece of information from the xml contents onto the dashboard?
Take the slidebar as an example. How to display the slidebar labels (i.e. 2015 and 2019) from parsing the <year> tag and selecting the max and min values?
And, can you recommend some reading materials for me to learn the whole process from xml to dashboard? Many many thanks in advance.
(P.S. I've tried to use xml package instead, since there are some standard arguments to find the max, min, and avg values of attributes. But I ran into another big error -
Error in function (type, msg, asError = TRUE) :
error:1407742E:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert protocol version
What should I do? My R version is 4.0.5 (2021-03-31).)

Answer 1

You can use xml2::as_list to create a tibble from the XML tree.
Moreover, you can use shiny::updateSliderInput to update UI slider ranges:
library(shiny)
library(shinydashboard)
library(dplyr)
library(tidyverse)
library(reshape)
library(scales)
library(xml2)
vec <- c(
"No of case" = "no_of_case",
"Minor Case" = "minor_case",
"All Non Fatal Case" = "all_non_fatal_case",
"Fatal Case" = "fatal_case"
)
ui <- fluidPage(sidebarLayout(
sidebarPanel(
checkboxGroupInput(
"feature",
"Feature",
vec
),
sliderInput(
"year",
"Year",
min = 2000,
max = 2001,
value = c(2000, 2001),
sep = "",
step = 1
)
),
mainPanel(tabsetPanel(
tabPanel("Plot", plotOutput("correlation_plot")),
tabPanel("Table", tableOutput("table"))
))
))
server <- function(input, output, session) {
xml <-
"https://www.labour.gov.hk/datagovhk/resource/ecd/ecd-figures.xml" %>%
read_xml()
table <-
xml %>%
xml_find_all(".//item") %>%
map(as_list) %>%
map(~ .x %>% as_tibble()) %>%
bind_rows() %>%
unnest(everything()) %>%
type_convert()
years <- table$year %>% unique()
updateSliderInput(
session = session,
inputId = "year",
min = min(years),
max = max(years),
value = c(min(years), max(years)) # current selected range
)
sub_table <- reactive({
table %>%
filter(year %in% input$year[1]:input$year[2]) %>%
select(c(year, input$feature))
})
output$correlation_plot <- renderPlot({
validate(need(input$feature, "Check at least one item."))
sub_table() %>%
pivot_longer(-year) %>%
ggplot(aes(x = year, y = value, color = name)) +
geom_line(size = 1) +
scale_x_continuous(
breaks = seq(input$year[1], input$year[2], by = 1)
)
})
output$table <- renderTable({
sub_table()
})
}
shinyApp(ui, server)