Space

# Space

**Session 12**

]

---

# Plan for today

.box-4.medium.sp-after[Maps and truth]

.box-2.medium.sp-after[Putting data on maps]

.box-5.medium.sp-after[GIS in R with **sf**]

---

layout: false
name: maps-truth
class: center middle section-title section-title-4 animated fadeIn

# Maps and truth

---

---

# John Snow and 1854 cholera epidemic

.pull-left.center[
<figure>
 <img src="img/12/800px-John_Snow.jpg" alt="John Snow" title="John Snow" width="60%">
 <figcaption>This Jo(h)n Snow knows things</figcaption>
</figure>
]

.pull-left.center[
.box-inv-4[10% of the population of Soho died in a week (!!)]

???

https://en.wikipedia.org/wiki/John_Snow

---

layout: false
class: bg-full
background-image: url("img/12/1092px-Snow-cholera-map-1.jpg")

???

https://commons.wikimedia.org/wiki/File:Snow-cholera-map-1.jpg

---

---

# The Broad Street pump

.pull-left-wide.center[
<figure>
 <img src="img/12/Snow-cholera-map.jpg" alt="John Snow's 1854 cholera map" title="John Snow's 1854 cholera map" width="68%">
</figure>
]

.pull-left-narrow[
<figure>
 <img src="img/12/John_Snow_memorial_and_pub.jpg" alt="The Broad Street Pump" title="The Broad Street Pump" width="100%">
</figure>
]

???

https://nl.wikibooks.org/wiki/Bestand:Snow-cholera-map.jpg

https://upload.wikimedia.org/wikipedia/commons/c/cb/John_Snow_memorial_and_pub.jpg

---

# Outright lies

.pull-left.center[
<figure>
 <img src="img/12/wp-bad-map.jpg" alt="Fake map" title="Fake map" width="90%">
</figure>
]

.pull-right.center[
<figure>
 <img src="img/12/bad-map-meme.png" alt="Fake map again" title="Fake map again" width="70%">
</figure>
]

???

Bottom map doesn't even show crime rates—it's the results from the 2012 presidential election

https://www.washingtonpost.com/news/fact-checker/wp/2016/11/16/no-the-viral-image-of-2016-election-results-and-2013-crime-rates-is-not-real/

https://me.me/i/electoral-map-2016-election-crime-rate-milo-democrats-are-as-3983235

---

# Fake maps and junk maps

.pull-left.center[
<figure>
 <img src="img/12/bot-designed-maps.png" alt="Fast Company on bot-designed maps" title="Fast Company on bot-designed maps" width="80%">
 <figcaption><a href="https://www.fastcompany.com/90230916/the-next-great-fake-news-threat-bot-designed-maps" target="_blank">“The next great fake news threat? Bot-designed maps”</a></figcaption>
</figure>
]

.pull-right.center[
<figure>
 <img src="img/12/candy-map.jpg" alt="Favorite candy by state" title="Favorite candy by state" width="100%">
</figure>
]

???

https://www.fastcompany.com/90230916/the-next-great-fake-news-threat-bot-designed-maps

https://www.reddit.com/r/funny/comments/dos6zx/finally_an_accurate_candy_map/

---

# Points can be useless

.center[
<figure>
 <img src="img/12/heatmap.png" alt="xkcd population maps" title="xkcd population maps" width="42%">
</figure>
]

???

https://xkcd.com/1138/

---

# Choropleths can be great

.center[
<figure>
 <img src="img/12/fall-foliage-2019.png" alt="2019 Fall foliage prediction map" title="2019 Fall foliage prediction map" width="65%">
 <figcaption><a href="https://smokymountains.com/fall-foliage-map/" target="_blank">Smoky Mountains 2019 Fall Foliage Prediction Map</a></figcaption>
</figure>
]

???

https://smokymountains.com/fall-foliage-map/

---

# Choropleths can distort

.center[
<figure>
 <img src="img/12/white-house-framed-map.png" alt="White House framed map of election results" title="White House framed map of election results" width="37%">
</figure>
]

???

https://thehill.com/blogs/blog-briefing-room/332927-trump-will-hang-map-of-2016-election-results-in-the-white-house

---

# Land doesn't vote

???

https://demcastusa.com/2019/11/11/land-doesnt-vote-people-do-this-electoral-map-tells-the-real-story/

[Cryptic command](https://stackoverflow.com/questions/31781238/using-ffmpeg-to-convert-gif-to-mp4-output-doesnt-play-on-android) to convert gif to mp4:

```text
ffmpeg -r 30 -i input.gif -movflags faststart -pix_fmt yuv420p -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" out.mp4
```

---

# Cartograms

&nbsp;

.pull-left-3.center[
<figure>
 <img src="img/12/countymap3070384.png" alt="2016 map by county" title="2016 map by county" width="100%">
</figure>
]

.pull-middle-3.center[
<figure>
 <img src="img/12/538-hexagon-cartogram.png" alt="FiveThirtyEight hex cartogram" title="FiveThirtyEight hex cartogram" width="100%">
</figure>
]

.pull-right-3.center[
<figure>
 <img src="img/12/countycart30701024.png" alt="2016 cartogram by county" title="2016 cartogram by county" width="100%">
</figure>
]

???

http://metrocosm.com/election-2016-map-3d/

---

layout: false
class: bg-full
background-image: url("img/12/Election2015_WinnerChangeMaps.jpg")

???

http://www.viewsoftheworld.net/?p=4570

---

.center[
<figure>
 <img src="img/12/2016_election_map_large.png" alt="xkcd 2016 election map" title="xkcd 2016 election map" width="70%">
</figure>
]

???

https://xkcd.com/1939/

---

---

# Projections

.box-inv-4.medium[[Animated world projections](https://bl.ocks.org/mbostock/raw/3711652/)]

???

Disable my video so OBS is happy

---

# World projections

---

# US projections

---

# Finding projection codes

.box-inv-4.small[[This](https://www.earthdatascience.org/courses/earth-analytics/spatial-data-r/understand-epsg-wkt-and-other-crs-definition-file-types/) is an excellent overview of how this all works]

.box-inv-4.small[And [this](https://web.archive.org/web/20200225021219/https://www.nceas.ucsb.edu/~frazier/RSpatialGuides/OverviewCoordinateReferenceSystems.pdf) is a really really helpful overview of all these moving parts]

---

# Which projection is best?

.box-inv-4.medium[None of them]

.box-inv-4.small[(but also ew mercator)]

---

layout: false
name: data-on-maps
class: center middle section-title section-title-2 animated fadeIn

# Putting data on maps

---

---

# Maps with lines

.center[
<figure>
 <img src="img/12/CA_Migration_v2_101-01.png" alt="Net migration between California and other states" title="Net migration between California and other states" width="55%">
 <figcaption><a href="https://www.census.gov/dataviz/visualizations/051/" target="_blank">US Census Bureau: Net migration between California and other states</a></figcaption>
</figure>
]

???

https://www.census.gov/dataviz/visualizations/051/

---

# Maps with lines

.center[
<figure>
 <img src="img/12/wind-map.png" alt="hint.fm wind map from Hurricane Sandy in 2012" title="hint.fm wind map from Hurricane Sandy in 2012" width="85%">
 <figcaption><a href="http://hint.fm/wind/index.html" target="_blank">hint.fm Live Wind Map</a></figcaption>
</figure>
]

???

http://hint.fm/wind/index.html

---

layout: false
class: bg-full
background-image: url("img/12/streams-lakes-bw-100-w-01.jpg")

???

https://kieranhealy.org/prints/rivers/

---

---

# Maps with points

.center[
<figure>
 <img src="img/12/7840356344_c8dda52c31_h.jpg" alt="Every hurricane since 1851, by IDV solutions" title="Every hurricane since 1851, by IDV solutions" width="70%">
 <figcaption><a href="https://www.flickr.com/photos/idvsolutions/7840356344/" target="_blank">Every hurricane since 1851, by IDV solutions</a></figcaption>
</figure>
]

???

https://www.flickr.com/photos/idvsolutions/7840356344/

---

# Maps with points

.center[
<figure>
 <img src="img/12/nyt-la-vaccinations.png" alt="NYT LA vaccinations" title="NYT LA vaccinations" width="90%">
 <figcaption><a href="https://www.nytimes.com/interactive/2015/02/06/us/california-measles-vaccines-map.html" target="_blank">The New York Times, "Vaccination Rates for Every Kindergarten in California</a></figcaption>
</figure>
]

???

https://www.nytimes.com/interactive/2015/02/06/us/california-measles-vaccines-map.html

---

# Maps with points

.center[
<figure>
 <img src="img/12/dc-photo-locations-small.jpg" alt="DC photo locations by locals and tourists" title="DC photo locations by locals and tourists" width="48%">
 <figcaption><a href="https://www.flickr.com/photos/walkingsf/4672195208/in/album-72157624209158632/" target="_blank">Locals vs. tourists in DC (blue = locals; red = tourists; yellow = unknown)</a></figcaption>
</figure>
]

???

https://www.flickr.com/photos/walkingsf/4672195208/in/album-72157624209158632/

---

# Voronoi maps

.pull-left.center[
<figure>
 <img src="img/12/voronoi-states.png" alt="Voronoi state boundaries" title="Voronoi state boundaries" width="100%">
 <figcaption><a href="http://vizual-statistix.tumblr.com/post/48625446909/these-are-voronoi-maps-of-the-contiguous-usa" target="_blank">Voroni state boundaries, by Seth Kadish</a></figcaption>
</figure>
]

.pull-right.center[
<figure>
 <img src="img/12/voronoi-nba.png" alt="Voronoi state boundaries" title="Voronoi state boundaries" width="100%">
 <figcaption><a href="https://www.reddit.com/r/nba/comments/27got5/which_team_is_closest_to_you_a_voronoi_diagram/" target="_blank">Closest NBA teams</a></figcaption>
</figure>
]

???

http://vizual-statistix.tumblr.com/post/48625446909/these-are-voronoi-maps-of-the-contiguous-usa

https://www.reddit.com/r/nba/comments/27got5/which_team_is_closest_to_you_a_voronoi_diagram/

---

# Maps with shapes

.center[
<figure>
 <img src="img/12/nyt-aca-map.png" alt="NYT: States Where Insured Could Renew Plans Before Change by Obama" title="NYT: States Where Insured Could Renew Plans Before Change by Obama" width="70%">
</figure>
]

???

https://archive.nytimes.com/www.nytimes.com/interactive/2013/11/20/us/which-states-will-allow-old-health-policies-to-be-renewed.html

---

# Small multiples that look like maps

.center[
<figure>
 <img src="img/08/geofacet.png" alt="geofacet package" title="geofacet package" width="65%">
 <figcaption><code>facet_geo()</code> in the <a href="https://hafen.github.io/geofacet/" target="_blank">geofacet package</a></figcaption>
</figure>
]

---

layout: false
name: gis-sf
class: center middle section-title section-title-5 animated fadeIn

# GIS in R with **sf**

---

---

# Shapefiles

.center[
<figure>
 <img src="img/12/shapefile-raw.png" alt="Shapefile folder structure" title="Shapefile folder structure" width="30%">
</figure>
]

---

# Structure of a shapefile

```r
library(sf)
world_shapes <- read_sf("data/ne_110m_admin_0_countries/ne_110m_admin_0_countries.shp")
```

```
## Simple feature collection with 7 features and 3 fields
## Geometry type: MULTIPOLYGON
## Dimension: XY
## Bounding box: xmin: -180 ymin: -18 xmax: 180 ymax: 83
## Geodetic CRS: WGS 84
## # A tibble: 7 x 4
## TYPE GEOUNIT ISO_A3 geometry
## <chr> <chr> <chr> <MULTIPOLYGON [°]>
## 1 Sovereign … Fiji FJI (((180 -16, 180 -17, 179 -17, 179 -17, 179 -17, 179 …
## 2 Sovereign … Tanzania TZA (((34 -0.95, 34 -1.1, 38 -3.1, 38 -3.7, 39 -4.7, 39 …
## 3 Indetermin… Western Sahara ESH (((-8.7 28, -8.7 28, -8.7 27, -8.7 26, -12 26, -12 2…
## 4 Sovereign … Canada CAN (((-123 49, -123 49, -125 50, -126 50, -127 51, -128…
## 5 Country United States … USA (((-123 49, -120 49, -117 49, -116 49, -113 49, -110…
## 6 Sovereign … Kazakhstan KAZ (((87 49, 87 49, 86 48, 86 47, 85 47, 83 47, 82 46, …
## 7 Sovereign … Uzbekistan UZB (((56 41, 56 45, 59 46, 59 46, 60 45, 61 44, 62 44, …
```
]

---

# Where to find shapefiles

.box-inv-5.sp-after[[US Census Bureau](https://www.census.gov/geographies/mapping-files/time-series/geo/carto-boundary-file.html) for US maps]

.center[
<figure>
 <img src="img/12/shapefile-search.png" alt="Search for shapefiles" title="Search for shapefiles" width="50%">
</figure>
]

---

# Scales

.pull-left-3[
<figure>
 <img src="img/12/download_thumbs_10m.jpg" alt="10m scale" title="10m scale" width="100%">
</figure>

.box-inv-5.small[1:10m = 1:10,000,000]

.box-inv-5.small[1 cm = 100 km]
]

.pull-middle-3[
<figure>
 <img src="img/12/download_thumbs_50m.jpg" alt="50m scale" title="50m scale" width="100%">
</figure>

.box-inv-5.small[1:50m = 1:50,000,000]

.box-inv-5.small[ 1cm = 500 km]
]

.pull-right-3[
<figure>
 <img src="img/12/download_thumbs_110m.jpg" alt="110m scale" title="110m scale" width="100%">
</figure>

.box-inv-5.small[1:110m = 1:110,000,000]

.box-inv-5.small[1 cm = 1,100 km]
]

&nbsp;

---

# Latitude and longitude

---

# The magic `geometry` column

.box-inv-5[As long as you have a magic `geometry` column, **all you need** to do to plot maps is `geom_sf()`]

```r
ggplot() +
  geom_sf(data = world_shapes)
```
]

---

# The magic `geometry` column

```r
ggplot() +
  geom_sf(data = world_shapes) +
  coord_sf(crs = "+proj=merc")
```
]

---

# The magic `geometry` column

```r
ggplot() +
  geom_sf(data = world_shapes) +
  coord_sf(crs = "+proj=robin")
```
]

---

# Use aesthetics like normal

```r
ggplot() +
  geom_sf(data = world_shapes, 
          aes(fill = POP_EST),
          color = "white", size = 0.15) +
  coord_sf(crs = "+proj=robin") +
  scale_fill_gradient(labels = scales::comma) +
  labs(fill = NULL) +
  theme_void() +
  theme(legend.position = "bottom")
```
]

---

# No `geometry` column?

.pull-left-narrow.small-code[

```r
other_data
```

```
## # A tibble: 2 x 3
## city long lat
## <chr> <dbl> <dbl>
## 1 Atlanta -84.4 33.8
## 2 Washington, DC -77.1 38.9
```
]

.pull-right-wide.small-code[

```r
other_data %>% 
  st_as_sf(coords = c("long", "lat"), 
           crs = st_crs("EPSG:4326")) 
```

```
## Simple feature collection with 2 features and 1 field
## Geometry type: POINT
## Dimension: XY
## Bounding box: xmin: -84 ymin: 34 xmax: -77 ymax: 39
## Geodetic CRS: WGS 84
## # A tibble: 2 x 2
## city geometry
## * <chr> <POINT [°]>
## 1 Atlanta (-84 34)
## 2 Washington, DC (-77 39)
```
]

---

# **sf** is for all GIS stuff

.box-inv-5.sp-after[Anything else related to geography!]

.box-inv-5[See [here](https://bookdown.org/robinlovelace/geocompr/intro.html) or [here](https://bookdown.org/lexcomber/brunsdoncomber2e/Ch5.html) for full textbooks]

---

# `geom_sf()` is today’s standard

.box-inv-5[You'll sometimes find older tutorials and StackOverflow answers about using `geom_map()` or **ggmap** or other things]

.box-inv-5.sp-after[Those still work, but they don't use the same magical **sf** system with easy-to-convert projections and other GIS stuff]

.box-5.medium[Stick with **sf** and `geom_sf()` and your life will be easy]