Data Visualization

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# Data Visualization
## Alternatives to maps
### Andrew Irwin, <a href="mailto:a.irwin@dal.ca" class="email">a.irwin@dal.ca</a>
### Math & Stats, Dalhousie University
### 2021-03-19 (updated: 2021-03-06)

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# Plan

* When is a map not appropriate for geospatial data?

* Tile geometry

* Heatmaps with dendrograms

* Specialized heatmap for the USA

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### Why shouldn't I use a map?

* Always think about the purpose

* Is geography the most important feature?

* Are you showing points or areas?

* Will the area of a region complicate interpretation?

* Is the spatial extent one dimensional? What could you do with the other dimension?

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### Summary

* Maps are very effective for showing points where spatial location is the primary information

* To show quantitative data varying along a transcect, a line or dot plot may be better

* Colour shows larger/smaller, positive/negative, but does not show quantitative values well

* Heatmaps (2 dimensional tiles of colours) can be a good alternative

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### COVID-19 cases & geom_tile

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### Same data with ggheatmap

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### Scale columns to have sum 1

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### Specialized maps of USA

```r
library(statebins)
load("../static/election.rda")
m4 <- election %>% ggplot(aes(state = state, fill = pct_trump)) +
  geom_statebins() +
  theme_statebins() +
  labs(fill="Percent Trump")
```

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### Specialized maps of USA

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# Further reading

* Course notes

* Healy Chapter 7

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## Task

* Task 16 as described in repository