Maps and plots with ColOpenData"
In ColOpenData: Download Colombian Demographic, Climate and Geospatial Data

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  eval = identical(tolower(Sys.getenv("NOT_CRAN")), "true")
)

::: {style="text-align: justify;"} ColOpenData can be used to access open geospatial data from Colombia. This data is retrieved from the National Geostatistical Framework (MGN), published by Departamento Administrativo Nacional de Estadística (DANE). The MGN contains the political-administrative division and is used to reference census statistical information.

This package contains the 2018's version of the MGN, which also included a summarized version of the National Population and Dwelling Census (CNPV) in different aggregation levels. Each level is stored in a different dataset, which can be retrieved using the download_geospatial() function, which requires three arguments:

spatial_level character with the spatial level to be consulted
simplified logical for indicating if the downloaded spatial data should be a simplified version of the geometries. Simplified versions are lighter but less precise, and are recommended for easier applications like plots. Default is \code{TRUE}.
include_geom logical for including (or not) geometry. Default is TRUE
include_cnpv logical for including (or not) CNPV demographic and socioeconomic information Default is TRUE.

Available levels of aggregation come from the official spatial division provided by DANE, with their names corresponding to: :::

code <- c(
  "DPTO", "MPIO",
  "MPIOCL", "MZN",
  "SECR", "SECU",
  "SETR", "SETU",
  "ZU"
)
level <- c(
  "Department", "Municipality",
  "Municipality including Class", "Block", "Rural Sector", "Urban Sector",
  "Rural Section", "Urban Section", "Urban Zone"
)
dictionary_key <- c(
  "DANE_MGN_2018_DPTO", "DANE_MGN_2018_MPIO",
  "DANE_MGN_2018_MPIOCL", "DANE_MGN_2018_MZN",
  "DANE_MGN_2018_SECR", "DANE_MGN_2018_SECU",
  "DANE_MGN_2018_SETR", "DANE_MGN_2018_SETU",
  "DANE_MGN_2018_ZU"
)

mgncnpv <- data.frame(
  Code = code, Level = level, Name = dictionary_key,
  stringsAsFactors = FALSE
)
knitr::kable(mgncnpv)

::: {style="text-align: justify;"} In this vignette you will learn:

How to download geospatial data using ColOpenData.
How to use census data included in geospatial datasets.
How to visualize spatial data using leaflet and ggplot2.

We will be using geospatial data at the level of Department ("dpto") and we will calculate the percentage of dwellings with internet connection at each department. Later, we will build some plots using the previously mentioned approaches for dynamic and static plots.

We will start by importing the needed libraries. :::

library(ColOpenData)
library(dplyr)
library(sf)
library(ggplot2)
library(leaflet)

::: {style="text-align: justify;"} Disclaimer: all data is loaded to the environment in the user's R session, but is not downloaded to user's computer. Spatial datasets can be very long and might take a while to be loaded in the environment :::

Downloading geospatial data

::: {style="text-align: justify;"} First, we download the data using the function download_geospatial(), including the geometries and the census related information. The simplified parameter is used to download a lighter version, since simple plots do not require precise spatial information. :::

dpto <- download_geospatial(
  spatial_level = "dpto",
  simplified = TRUE,
  include_geom = TRUE,
  include_cnpv = TRUE
)

head(dpto)

::: {style="text-align: justify;"} To understand which column contains the internet related information, we will need the corresponding dataset dictionary. To download the dictionary we can use the geospatial_dictionary() function. This function uses as parameters the dataset name to download the associated information and language of this information. For further information please refer to the documentation on dictionaries previously mentioned. :::

dict <- geospatial_dictionary(spatial_level = "dpto", language = "EN")

head(dict)

::: {style="text-align: justify;"} To calculate the percentage of dwellings with internet connection, we will need to know the number of dwellings with internet connection and the total of dwellings in each department. From the dictionary, we get that the number of dwellings with internet connection is [viv_internet]{.underline} and the total of dwellings is [viviendas]{.underline}. We will calculate the percentage as follows: :::

internet_cov <- dpto %>% mutate(internet = round(viv_internet / viviendas, 2))

Static plots (ggplot2)

::: {style="text-align: justify;"} ggplot2 can be used to generate static plots of spatial data by using the geometry geom_sf(). Color palettes and themes can be defined for each plot using the aesthetic and scales, which can be consulted in the ggplot2 documentation. We will use a gradient with a two-color diverging palette, to make the differences more visible. :::

ggplot(data = internet_cov) +
  geom_sf(mapping = aes(fill = internet), color = NA) +
  theme_minimal() +
  theme(
    plot.background = element_rect(fill = "white", colour = "white"),
    panel.background = element_rect(fill = "white", colour = "white"),
    panel.grid = element_blank(),
    axis.text = element_blank(),
    axis.ticks = element_blank()
  ) +
  scale_fill_gradient("Percentage", low = "#10bed2", high = "#deff00") +
  ggtitle(
    label = "Internet coverage",
    subtitle = "Colombia"
  )

Dynamic plots (leaflet)

::: {style="text-align: justify;"} For dynamic plots, we can use leaflet, which is an open-source library for interactive maps. To create the same plot we first will create the color palette. :::

colfunc <- colorRampPalette(c("#10bed2", "#deff00"))
pal <- colorNumeric(
  palette = colfunc(100),
  domain = internet_cov[["internet"]]
)

::: {style="text-align: justify;"} With the previous color palette we can generate the interactive plot. The package also includes open source maps for the base map like OpenStreetMap and CartoDB. For further details on leaflet, please refer to the package's documentation. :::

leaflet(internet_cov) %>%
  addProviderTiles(providers$CartoDB.Positron) %>%
  addPolygons(
    stroke = TRUE,
    weight = 0,
    color = NA,
    fillColor = ~ pal(internet_cov[["internet"]]),
    fillOpacity = 1,
    popup = paste0(internet_cov[["internet"]])
  ) %>%
  addLegend(
    position = "bottomright",
    pal = pal,
    values = ~ internet_cov[["internet"]],
    opacity = 1,
    title = "Internet Coverage"
  )