Introduction to Data Science

class: center, middle, inverse, title-slide

.title[
# Introduction to Data Science
]
.subtitle[
## Week 7: Maps (cont’d)
]
.author[
### Ugur Aytun
]
.institute[
### METU, Department of Economics | ECON 413
]

---

---
# Maps

- This week we proceed with the topic of maps.

- Last week we uploaded our own map of Turkey, which was a shapefile containing the administrative borders of Turkey's provinces.

- New packages are introduced, such as `rnaturalearth` and `rnaturalearthdata` for geographical data without requiring shapefiles, and `sf` for handling spatial data in R.

---
# Loading Required Libraries, set the working directory and load the map of the world

.scrollable[

``` r
library(sf)
```

```
## Warning: package 'sf' was built under R version 4.3.3
```

```
## Linking to GEOS 3.11.2, GDAL 3.8.2, PROJ 9.3.1; sf_use_s2() is TRUE
```

``` r
library("rnaturalearth")
```

```
## Warning: package 'rnaturalearth' was built under R version 4.3.3
```

``` r
library("rnaturalearthdata")
```

```
## Warning: package 'rnaturalearthdata' was built under R version 4.3.3
```

```
## 
## Attaching package: 'rnaturalearthdata'
```

```
## The following object is masked from 'package:rnaturalearth':
## 
##     countries110
```

``` r
library("ggplot2")
```

```
## Warning: package 'ggplot2' was built under R version 4.3.3
```

``` r
library(data.table)
```

```
## Warning: package 'data.table' was built under R version 4.3.3
```

``` r
world <- ne_countries(scale = "medium", returnclass = "sf")
class(world)
```

```
## [1] "sf"         "data.frame"
```
]

---
# World map

.scrollable[

``` r
# plot the world map
ggplot(data = world) + geom_sf()
```

![](data:image/png;base64,#week_7_files/figure-html/unnamed-chunk-2-1.png)

``` r
# plot the world map with a black border
ggplot(data = world) + geom_sf() + theme_bw()
```

![](data:image/png;base64,#week_7_files/figure-html/unnamed-chunk-2-2.png)

``` r
# plot the world map with a black border and no background
ggplot(data = world) + geom_sf() + theme_void()
```

![](data:image/png;base64,#week_7_files/figure-html/unnamed-chunk-2-3.png)

``` r
# plot the world map with a black border and no background
ggplot(data = world) + geom_sf() + theme_bw() +
  labs(title = "World map", 
       subtitle = paste0(length(unique(world$sov_a3)), " countries"), 
       x = "Longitude", y = "Latitude")
```

![](data:image/png;base64,#week_7_files/figure-html/unnamed-chunk-2-4.png)

``` r
# create titles object
ctitles <-   labs(title = "World map", 
                  subtitle = paste0(length(unique(world$sov_a3)), " countries"), 
                  x = "Longitude", y = "Latitude")

# add a title
ggplot(data = world) + 
  geom_sf() + 
  theme_bw() + ctitles
```

![](data:image/png;base64,#week_7_files/figure-html/unnamed-chunk-2-5.png)

``` r
# fill the countries with a color
ggplot(data = world) + 
  geom_sf(color = "black", fill = "lightblue") + 
  theme_bw() + ctitles
```

![](data:image/png;base64,#week_7_files/figure-html/unnamed-chunk-2-6.png)

``` r
# add coordinate numbers
ggplot(data = world) + 
  geom_sf(color = "black", fill = "lightblue") + 
  coord_sf(ylim = c(-65, 90), expand = FALSE) +
  theme_bw() + ctitles
```

![](data:image/png;base64,#week_7_files/figure-html/unnamed-chunk-2-7.png)
]

---
# World and Turkey map

.scrollable[

``` r
# color the countries by economic development
ggplot(data = world) + 
  geom_sf(aes(fill = economy)) + 
  coord_sf(ylim = c(-65, 90), expand = FALSE) +
  theme_bw() + ctitles +
  scale_fill_viridis_d(option = "plasma")
```

![](data:image/png;base64,#week_7_files/figure-html/unnamed-chunk-3-1.png)

``` r
# color the countries by population
ggplot(data = world) + 
  geom_sf(aes(fill = pop_est)) + 
  coord_sf(ylim = c(-65, 90), expand = FALSE) +
  theme_bw() + ctitles +
  scale_fill_viridis_c(option = "plasma", trans = "sqrt")
```

![](data:image/png;base64,#week_7_files/figure-html/unnamed-chunk-3-2.png)

``` r
# color the countries by population (inverse color scale)
ggplot(data = world) + 
  geom_sf(aes(fill = pop_est)) + 
  coord_sf(ylim = c(-65, 90), expand = FALSE) +
  theme_bw() + ctitles +
  scale_fill_viridis_c(option = "plasma", trans = "sqrt", direction = -1)
```

![](data:image/png;base64,#week_7_files/figure-html/unnamed-chunk-3-3.png)

``` r
# color the countries by population (inverse color scale) with a different projection
ggplot(data = world) + 
  geom_sf(aes(fill = pop_est)) + 
  theme_bw() + ctitles +
  scale_fill_viridis_c(option = "plasma", trans = "sqrt", direction = -1) +
  coord_sf(crs = st_crs(3035))
```

![](data:image/png;base64,#week_7_files/figure-html/unnamed-chunk-3-4.png)

``` r
# Turkey map

turkey <- ne_states(country = "turkey", returnclass = "sf")

class(turkey)
```

```
## [1] "sf"         "data.frame"
```

``` r
ggplot(data = turkey) + 
  geom_sf() + 
  theme_void() + 
  labs(title = "Turkey map")
```

![](data:image/png;base64,#week_7_files/figure-html/unnamed-chunk-3-5.png)

``` r
# add province name
ggplot(data = turkey) + 
  geom_sf() + 
  geom_sf_text(aes(latitude, longitude, label = name), size = 2) +
  theme_void() + 
  labs(title = "Turkey map")
```

```
## Warning in st_point_on_surface.sfc(sf::st_zm(x)): st_point_on_surface may not
## give correct results for longitude/latitude data
```

![](data:image/png;base64,#week_7_files/figure-html/unnamed-chunk-3-6.png)

``` r
# different color
ggplot(data = turkey) +
  geom_sf(color = "black", fill = "red") + 
  geom_sf_text(aes(latitude, longitude, label = name), size = 2) +
  theme_void() + 
  labs(title = "Turkey map")
```

```
## Warning in st_point_on_surface.sfc(sf::st_zm(x)): st_point_on_surface may not
## give correct results for longitude/latitude data
```

![](data:image/png;base64,#week_7_files/figure-html/unnamed-chunk-3-7.png)

]