custom-map.Rmd

---
title: "Making Custom Maps with tmap"
author: "Angela Li"
date: "5/22/2019"
output: html_document
---

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

## Animated Map Example

This is our ultimate goal!
```{r eval=FALSE}
library(sf)
library(tidyverse)
library(spData)
library(tmap)
m_save = world %>% filter(continent != "Antarctica") %>% 
  tm_shape() + 
  tm_polygons() +
  tm_shape(urban_agglomerations) +
  tm_dots(size = "population_millions", title.size = "Population (m)", alpha = 0.5, col = "red") +
  tm_facets(along = "year", free.coords = FALSE)
tmap::tmap_animation(tm = m_save, filename = "/tmp/urban-animated.gif", width = 1200, height = 800)
magick::image_read("/tmp/urban-animated.gif")
```

# Load packages
```{r message=FALSE}
library(sf) # for spatial data
library(spData) # sample data I'm working with
library(tidyverse) # for data wrangling
library(tmap) # for custom maps
```

# Explore my data
```{r}
head(urban_agglomerations)
head(world)

summary(urban_agglomerations)
str(urban_agglomerations) # base R version
glimpse(urban_agglomerations) # tidyverse version - I prefer this one
class(urban_agglomerations) # tells you what type of object this is
dim(urban_agglomerations) # dimensions of data
```

# Make a ggplot2 map
```{r}
ggplot() +
  geom_sf(data = urban_agglomerations)
```

```{r}
ggplot() +
  geom_sf(data = world) +
  geom_sf(data = urban_agglomerations)
```

# Try making the same map in tmap
```{r}
tm_shape(world) +
  tm_polygons() +
  tm_shape(urban_agglomerations) +
  tm_dots(size = "population_millions") +
  tm_compass() +
  tm_scale_bar(position = c("left", "bottom")) +
  tm_legend(legend.outside = TRUE) +
  tm_layout(panel.show = TRUE, panel.labels = c("World population in 1950"))
```