leaflet_markdown.Rmd

---
title: "Leaflet wordlmap"
output: html_document
runtime: shiny
---

Loading libraries

```{r, echo = FALSE}
library(leaflet.extras)
library(dplyr)
```

Create a data set from daily reports

```{r, echo = FALSE}
source("shiny/data_gen.R")
covid_global_confirmed <- generate_all_from_daily("shiny/COVID-19/csse_covid_19_data/csse_covid_19_daily_reports")
```

Build up the basics of the app, including a slider for the date:

```{r, echo = TRUE, warning=FALSE}
# Extract dates
all_dates <- covid_global_confirmed$date %>% unique() %>% as.POSIXct(origin = "1970-01-01")

# Calculate some basics
only_numeric <- sort(as.numeric(unique(covid_global_confirmed$active)))
col_pal <- colorNumeric(
    c(rep("#FFFFFF", 1), viridisLite::viridis(99)),
    domain = c(min(only_numeric, na.rm = TRUE), max(only_numeric, na.rm = T))
  )

max_val <- max(only_numeric, na.rm = T)

# Create Date input
shiny::sliderInput(inputId = "datum", min = min(all_dates), max = max(all_dates), value = min(all_dates), label = "Date", timeFormat="%Y-%m-%d")

# Extract the current date
curr_date <- reactiveVal( as.character(Sys.Date() + 1))

```


Create a map using leaflet

```{r, echo = TRUE, warning=FALSE}
# Print out leaflet map
renderLeaflet({
  date_to_choose <- as.character(input$datum)
  
  
  date_to_choose <- if (is.null(input$datum)) {
    as.character(Sys.Date() - 1)
  } else {
    as.character(input$datum)
  }
  
  # Filter the data
  data_for_display <- covid_global_confirmed %>%
    filter(date == as.character(date_to_choose)) %>%
    select(Lat, Long, active, date, Combined_Key) %>%
    filter(active > 0) %>%
    filter(!is.na(Long) & !is.na(Lat)) %>%
    mutate(active_scaled = case_when(
      grepl(pattern = "\\,\\s{0,1}US", x = Combined_Key) &
        as.Date(date_to_choose, origin = "1970-01-01") > as.Date("2020-03-21", origin = "1970-01-01") ~ scales::rescale(
          x = active, from = c(0, max_val), to = c(12000, 650000)
        ),
      TRUE ~ scales::rescale(x = active, from = c(0, max_val), to = c(60000, 450000))
    ),
    text = paste0(as.character(Combined_Key), "\n", active),
    color = col_pal(active)
    ) %>%
    arrange(active)
  
  # Create the map
  leaflet() %>% addProviderTiles(providers$ CartoDB.Positron) %>%
    setView(0,0, 2) %>%
    clearGroup(curr_date()) %>%
    addCircles(data = data_for_display, lng = ~Long, lat = ~Lat,
               radius = ~active_scaled, popup = ~text, fillColor = ~color, stroke = FALSE, fillOpacity = 0.5,
               group = stringr::str_match(date_to_choose, "\\d{4}\\-\\d{2}\\-\\d{2}")[1,1]
    )
})


```