_topogram.Rmd

---
title: "Cartogrammes"
author: "State of the R"
date: "24-28/08/2020"
output: html_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE, warning = FALSE)
```

`topogram` permet de créer des cartogrammes, c'est à dire des cartes pour lesquelle la surface des territoires représentés est proportionnelle à une variable.

Nous allons représenter le nombre des victimes du coronavirus par pays.

```{r, message=FALSE}
# remotes::install_github("RamiKrispin/coronavirus")
library(coronavirus)
library(tidyverse)
```

On récupère et met en forme le jeu de donnée des cas de coronavirus au `r Sys.Date()`.

```{r}
df_covid <-
  coronavirus %>%
  filter(type == "death") %>%
  group_by(country) %>%
  summarise(total_death = sum(cases), .groups = "drop") %>% # sommer les morts journaliers
  mutate(country = case_when(country == "US" ~ "United States", # pour le left_join()
                             country == "Congo (Kinshasa)" ~ "Dem. Rep. Congo",
                             country == "Congo (Brazzaville)" ~ "Congo",
                             country == "Cote d'Ivoire" ~ "Côte d'Ivoire",
                             country == "Central African Republic" ~ "Central African Rep.",
                             country == "Taiwan*" ~ "Taiwan",
                             country == "Equatorial Guinea" ~ "Eq. Guinea",
                             country == "South Sudan" ~ "S. Sudan",
                             country == "Western Sahara" ~ "W. Sahara",
                             country == "Korea, South" ~ "Korea",
                             country == "Czechia" ~ "Czech Rep.",
                             country == "Laos" ~ "Lao PDR",
                             country == "Bosnia and Herzegovina" ~ "Bosnia and Herz.",
                             TRUE    ~ country), # il reste d'autres inadéquations dans les noms
         total_death = total_death + 1) # pour éviter les 0
df_covid
```

On récupère la carte du monde et on la fusionne le jeu de données du coronavirus.

```{r}
# install.packages("rnaturalearth")
# remotes::install_github("dreamRs/topogram")
# remotes::install_github("ropensci/rnaturalearthhires")
library(rnaturalearth)
library(coronavirus)
library(topogram)
library(sf)
```


```{r}
world_covid <- 
  countries110 %>% 
  st_as_sf() %>% 
  left_join(df_covid, by = c("name" = "country")) %>% 
  drop_na(total_death) %>% 
  dplyr::select(name, total_death)
world_covid
```

La fontion `topogram` fait le travail.

```{r}
topogram(shape = world_covid,
         value = "total_death",
         tooltip_label = ~ name,
         n_iteration = 100,
         unit_value = "deaths",
         format_value = ".2s") %>% # D3 format for two significant digits
  add_labs(title = "Number of death by Covid-19") %>%
  add_legend(title = "", orientation = "vertical",
             label_format = ".2s")
```