Data Visualization

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# Data Visualization
## Theme
### Andrew Irwin, <a href="mailto:a.irwin@dal.ca" class="email">a.irwin@dal.ca</a>
### Math & Stats, Dalhousie University
### 2021-03-26 (updated: 2021-03-12)

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# Plan

* What is the `theme` of a visualization?

* Ready-to-use themes

* Titles

* Text size, colour, bold, italics, and more

* Spacing and positioning

---
### Starting figure

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### Ready to use themes

```r
p1 + theme_bw()
```

---
### Ready to use themes

```r
p1 + theme_classic()
```

<img src="32-theme_files/figure-html/unnamed-chunk-3-1.svg" width="70%" style="display: block; margin: auto;" />
---
### More themes

* `theme_dark`, `theme_gray`, `theme_light`

* From `ggthemes`: `theme_wsj`, `theme_tufte`, `theme_fivethirtyeight`, `theme_economist`, `theme_clean`

---
### All text larger

```r
p1 + theme(text = element_text(size=22))
```

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### Sizes for different elements

```r
p1 + theme(axis.text.x = element_text(size=16),
           axis.title.y = element_text(size=18),
           legend.title = element_text(size=16),
           legend.text = element_text(size=18),
           plot.title = element_text(size=21),
           plot.subtitle = element_text(size=20)) +
  labs(x = "Year", 
       y = "Life Expectancy at birth",
       title = "Life expectancy averaged by continent",
       subtitle = "From Gapminder.org")
```

---
### Other features of text

```r
p1 + labs(title = "Average life expectancy") + 
  theme(plot.title = element_text(family = "serif",
                                  face = "italic",
                                  color = "blue",
                                  size = 30,
                                  hjust = 1, 
                                  lineheight = 2))
```

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### Fancy text: ggtext

```r
library(ggtext)
p1 + labs(title = "**Gapminder** data for _life expectancy_<sup>1</sup>",
          caption = "<sup>1</sup>from gapminder.org") +
  theme(plot.title = element_markdown(size = 24),
        plot.caption = element_markdown(size = 13))
```

---
### Move and redesign the legend

```r
p1 + theme(legend.position = "top",
           legend.direction = "horizontal",
           legend.text = element_text(size = 11, vjust = 0.5),
           legend.title = element_text(size = 12, vjust = 0.5),
           legend.key.size = unit(0.9, "cm"))
```

---
### Move and redesign the legend

```r
p1 + theme_bw() + theme(legend.position = c(0.03, 0.98),
                        legend.justification = c(0,1),
           legend.direction = "vertical",
           legend.background = element_rect(fill = "transparent"),
           legend.text = element_text(size = 10, vjust = 0.5),
           legend.title = element_blank(),
           legend.key.size = unit(0.8, "cm")) + 
  guides(color = guide_legend(ncol = 3))
```

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### Formatting numbers on scales

```r
p1 + scale_x_continuous(labels = scales::dollar) +
  scale_y_continuous(labels = scales::percent) + # also comma
  theme(axis.text = element_text(size=14))
```

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# Further reading

* Course notes

* Healy and Wilke sections on colour

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## Task

* Practice using colour

* No assigned task