A glance at the code of Global Coffee Trade

line_chart_server.R

# This part of the code shows how I create the line chart in the "Trend" tab
# Packages used: dplyr, shiny, shinydashboard, googleVis
# Overview:
# 1. create reactive object to read input from the ui function
# 2. render chart
# line chart (time series) to see how attributes change over time for a particular country
coffee_over_time = reactive({
    # validate if user select the desired input 
    validate(
        need(input$checked != "", "Please check at least one variable in category"),
        need(input$country_nm != "", "Please select a country"),
        need(input$type_for_line != "", "Please select a unit")
    )
    # get the dataframe based on user selection
    coffee_subset = coffee %>% filter(region == input$country_nm) 
    n = length(input$checked)
    # check the year range based on country selected
    df = data.frame("year" = min(coffee_subset$year): max(coffee_subset$year))
    for (i in 1:n) {
        # filter df based on country selected
        temp_df = filter(coffee_subset, Attribute_Description == input$checked[i])
        # select data with unit selected
        temp_df = temp_df[,c(4, which(names(temp_df) == input$type_for_line))]
        names(temp_df) = c("year", input$checked[i])
        df = full_join(df, temp_df) %>% arrange(year)
    }
    df = unique(df)
    df
})
# render line chart (time series)
output$line_chart = renderGvis(
    gvisLineChart(coffee_over_time(),
                  option = list(
                      hAxis = "{title:'Year'}",
                      legend= "{position: 'bottom'}",
                      height = 400
                  ))
)

line_chart_ui.R

# This part of the code shows how I read user input 
# and render line chart in the "Trend" tab
# Overview:
# 1. get user input with unique id to pass to server function
# 2. place the line chart created in the server into the tab
tabItem(tabName = "line",
        # get user input
        box(checkboxGroupInput("checked", "Category", 
                               attribute_lst,
                               selected = attribute_lst[c(5,8)]), width = 4), 
        box(width = 4, selectizeInput("country_nm", "Country",
                                      region_lst, 
                                      selected = "European Union")),
        box(width = 4, selectizeInput("type_for_line", "Unit", 
                                      c("kg" = "kg","kg/gdp" = "kg_per_gdp",
                                        "kg/person" = "kg_per_person"), 
                                      selected = "kg_per_gdp")),
        # insert the line chart 
        box(status = "primary", solidHeader = TRUE,
            title = textOutput("line_info"),
            htmlOutput("line_chart", width = "100%"), width = 8)
        
)