Themes

# Themes
### Derek Ogle, May 2020

---

# Today's Goal

Learn how to provide specific control over all elements of a plot.

---

# Today's Goal

- Demonstrate built-in themes.

&nbsp;

--
- Demonstrate how to modify aspects of a plot with `theme()`.

&nbsp;

--
- Show how to create your own theme.

&nbsp;

--
- Demonstrate how to set a default theme for each plot.

---

# What is a Theme?

---

# What is a theme?

- Aspects of the graph not directly related to data.

--
  - Background color.
  - Grid line color and type.
  - Label font size, type, and margin.
  - Legend position, orientation, and margin.
  - Facet label, position, and margin.
  - etc.

---

# Built-in Themes

---

# Built-in Themes

- ggplot2 has 9 built-in themes.
  - `theme_gray()` (default)
  - `theme_bw()`
  - `theme_classic()`
  - `theme_minimal()`
  - `theme_dark()`
  - etc.

&nbsp;

--
- Other full themes are available in other packages; e.g., 
  - `theme_half_open()` from `cowplot` package.
  - `theme_tufte()` from `ggthemes` package.
  - `theme_excel()` from `ggthemes` package.
  - `theme_gdocs()` from `ggthemes` package.

---

---

# Built-in Themes

- All built-in themes have four arguments.

--
  - `base_size=`: "base size" of fonts (default is 11).
  - `base_family=`: "base family" of fonts (default depends on OS).
  - `base_line_size=`: "base size" of lines (default is 1/22nd of `base_size=`).
  - `base_rect_size=`: "base size" of rectangles (default is 1/22nd of `base_size=`).

&nbsp;

--
- Probably only ever change `base_size=` and `base_family=`.

---

```r
p 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/bases_non_seq_1_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
p + 
* theme_bw(
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/bases_non_seq_2_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
p + 
 theme_bw( 
* base_size=18,
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/bases_non_seq_3_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
p + 
 theme_bw( 
 base_size=18, 
* base_family="serif",
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/bases_non_seq_4_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
p + 
 theme_bw( 
 base_size=18, 
 base_family="serif", 
* base_rect_size=18/11
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/bases_non_seq_5_output-1.png" width="100%" />
]]

---

# Controlling Specific Aspects of a Theme

---

# Theme Elements

- Each theme is made up of many *elements*, organized into groups.

--
  - **Plot Elements**: effect the whole plot (e.g., title).
  - **Axis Elements**: effect the plot axes (e.g., ticks).
  - **Legend Elements**: effect legends (e.g., margin).
  - **Panel Elements**: effect plotting panels (e.g., gridlines).
  - **Facet Elements**: effect facets (e.g., "strip" color).

&nbsp;

--
- Elements are set using "element" or "setter" functions.

---

# Element (or Setter) Functions

- `element_text()`: Draws labels and headings.

--
  - Can control font `family=`, `face=` (e.g., bold and italic), `color=`, and `size=`; `hjust=`, `vjust=`, `angle=` (in degrees), `lineheight=`, and `margin=`.

&nbsp;

--
- `element_line()`: Draws lines.

--
  - Can control line `color=`, `size=`, and `linetype=`.

&nbsp;

--
- `element_rect()`: Draws rectangles (mostly used for backgrounds).

--
  - Can control `fill=`, `color=`, `size=`, and `linetype=`.

---

# Element (or Setter) Functions

- `element_blank()`: Draws nothing AND allocates no space to that object.

&nbsp;

--
- `margin()`: Sets margins around items.

--
  - Uses `t=` (top), `r=` (right), `b=` (bottom), `l=` (left).
  - Can set units with `unit=` (defaults to `pt`).

--
- `unit()`: Sets spacing or size.

--
  - Value in first argument.
  - Type of units in `units=` or second argument ... can be `"in"`, `"mm"`, `"cm"`, `"points"`, etc.

&nbsp;

--
- Which element/setter function to use depends on the theme element.

---

# Plot Elements

Element            | Setter           | Notes               
-------------------|------------------|------------
`plot.background=` | `element_rect()` | background of entire plot area
`plot.title=`      | `element_text()` | 
`plot.margin=`     | `margin()`       | margins around plot

---

```r
pb 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_plots_non_seq_1_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
* theme(
* plot.background=element_rect(fill="linen",color="blue"),
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_plots_non_seq_2_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 theme( 
 plot.background=element_rect(fill="linen",color="blue"), 
* plot.title=element_text(color="red",face="bold",size=24),
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_plots_non_seq_3_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 theme( 
 plot.background=element_rect(fill="linen",color="blue"), 
 plot.title=element_text(color="red",face="bold",size=24), 
* plot.margin=margin(b=1.5,r=1,unit="cm")
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_plots_non_seq_4_output-1.png" width="100%" />
]]

---

# Axis Elements

Element              | Setter           | Notes               
---------------------|------------------|---------------------------
`axis.line=`         | `element_line()` | line parallel to axis (may be hidden by `panel.border=`)
`axis.text=`         | `element_text()` | tick labels (all)
`axis.text.x=`       | `element_text()` | tick labels (x-axis)
`axis.text.y=`       | `element_text()` | tick labels (y-axis)
`axis.title=`        | `element_text()` | label for axis (all)
`axis.title.x=`      | `element_text()` | label for axis (x-axis)
`axis.title.y=`      | `element_text()` | label for axis (y-axis)            
`axis.ticks=`        | `element_line()` | axis tick marks
`axis.ticks.length=` | `unit()`         | axis tick mark lengths

---

```r
pb 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_axis_non_seq_1_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
* theme(
* axis.text=element_text(color="blue",size=14),
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_axis_non_seq_2_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 theme( 
 axis.text=element_text(color="blue",size=14), 
* axis.title.x=element_text(color="red",face="bold",size=24),
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_axis_non_seq_3_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 theme( 
 axis.text=element_text(color="blue",size=14), 
 axis.title.x=element_text(color="red",face="bold",size=24), 
* axis.title.y=element_text(color="green3",face="bold",size=36),
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_axis_non_seq_4_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 theme( 
 axis.text=element_text(color="blue",size=14), 
 axis.title.x=element_text(color="red",face="bold",size=24), 
 axis.title.y=element_text(color="green3",face="bold",size=36), 
* axis.ticks.length=unit(5,unit="mm")
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_axis_non_seq_5_output-1.png" width="100%" />
]]

---

# Panel Elements

Element               | Setter           | Description
----------------------|------------------|-------------------------------
`panel.background=`   | `element_rect()` | panel background (under data)
`panel.border=`       | `element_rect()` | panel border (over data)
`panel.grid.major=`   | `element_line()` | major grid lines
`panel.grid.major.x=` | `element_line()` | major grid lines (x-axis; vertical)
`panel.grid.major.y=` | `element_line()` | major grid lines (y-axis; horizontal)
`panel.grid.minor=`   | `element_line()` | minor grid lines
`panel.grid.minor.x=` | `element_line()` | minor grid lines (x-axis; vertical)
`panel.grid.minor.y=` | `element_line()` | minor grid lines (y-axis; horizontal)
`aspect.ratio=`       | numeric          | width:height ratio (of panel only)

---

```r
pb 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_panels_non_seq_1_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
* theme(
* panel.background=element_rect(fill="orange"),
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_panels_non_seq_2_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 theme( 
 panel.background=element_rect(fill="orange"), 
* panel.grid.major=element_line(color="gray30",linetype="dashed"),
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_panels_non_seq_3_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 theme( 
 panel.background=element_rect(fill="orange"), 
 panel.grid.major=element_line(color="gray30",linetype="dashed"), 
* panel.grid.minor.x=element_line(color="gray70",size=0.5),
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_panels_non_seq_4_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 theme( 
 panel.background=element_rect(fill="orange"), 
 panel.grid.major=element_line(color="gray30",linetype="dashed"), 
 panel.grid.minor.x=element_line(color="gray70",size=0.5), 
* panel.grid.minor.y=element_line(color="steelblue",size=0.5),
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_panels_non_seq_5_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 theme( 
 panel.background=element_rect(fill="orange"), 
 panel.grid.major=element_line(color="gray30",linetype="dashed"), 
 panel.grid.minor.x=element_line(color="gray70",size=0.5), 
 panel.grid.minor.y=element_line(color="steelblue",size=0.5), 
* panel.border=element_rect(
* color="red",size=2,
 ) 
* )
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_panels_non_seq_6_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 theme( 
 panel.background=element_rect(fill="orange"), 
 panel.grid.major=element_line(color="gray30",linetype="dashed"), 
 panel.grid.minor.x=element_line(color="gray70",size=0.5), 
 panel.grid.minor.y=element_line(color="steelblue",size=0.5), 
 panel.border=element_rect( 
 color="red",size=2, 
* fill="black"
 ) 
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_panels_non_seq_7_output-1.png" width="100%" />
]]

---

# Legend Elements

Element               | Setter           | Description
----------------------|------------------|-------------------------------
`legend.background=`  | `element_rect()` | background of entire legend
`legend.key=`         | `element_rect()` | background of legend keys
`legend.key.size=`    | `unit()`         |
`legend.key.height=`  | `unit()`         |
`legend.key.width=`   | `unit()`         |
`legend.margin=`      | `unit()`         | margin within legend
`legend.text=`        | `element_text()` | labels within legend
`legend.text.align=`  | 0-1              | 0=right, 1=left
`legend.title=`       | `element_text()` | legend name
`legend.title.align=` | 0-1              | 0=right, 1=left

---

```r
pb 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_legends1_non_seq_1_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
* theme(
* legend.background=element_rect(fill="orange"),
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_legends1_non_seq_2_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 theme( 
 legend.background=element_rect(fill="orange"), 
* legend.text=element_text(color="blue",size=18),
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_legends1_non_seq_3_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 theme( 
 legend.background=element_rect(fill="orange"), 
 legend.text=element_text(color="blue",size=18), 
* legend.title=element_text(color="red",size=24),
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_legends1_non_seq_4_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 theme( 
 legend.background=element_rect(fill="orange"), 
 legend.text=element_text(color="blue",size=18), 
 legend.title=element_text(color="red",size=24), 
* legend.key=element_rect(fill="yellow",color="black"),
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_legends1_non_seq_5_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 theme( 
 legend.background=element_rect(fill="orange"), 
 legend.text=element_text(color="blue",size=18), 
 legend.title=element_text(color="red",size=24), 
 legend.key=element_rect(fill="yellow",color="black"), 
* legend.key.size=unit(2,"mm")
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_legends1_non_seq_6_output-1.png" width="100%" />
]]

---

# Legend Elements (Positioning)

- Legend positioned with `legend.position=`.

--
  - Outside of panel region ... use `right` (default), `top`, `left`, or `bottom`.

--
  - Inside of panel region ... use `c(#,#)` ... with lower-left being `c(0,0)` and upper-right being `c(1,1)`.

&nbsp;

--
- Set "anchor point" of legend with `legend.justification=c(#,#)`.

--
  - Use in conjunction with `legend.position=c(#,#)`.
  - Values have same meaning ... lower-left is `c(0,0)`, upper-right is `c(1,1)`.

---

---

# Facet Elements

Element             | Setter           | Notes
--------------------|------------------|------------------------------------
`strip.background=` | `element_rect()` |
`strip.text=`       | `element_text()` |
`strip.text.x=`     | `element_text()` | horizontal strip text
`strip.text.y=`     | `element_text()` | vertical strip text (only w/ `facet_grid()`)
`panel.spacing=`    | `unit()`         | all margins between panels
`panel.spacing.x=`  | `unit()`         | vertical margin between panels
`panel.spacing.y=`  | `unit()`         | horizontal margin between panels

---

```r
pb 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_facets_non_seq_1_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
* facet_wrap(vars(grp))
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_facets_non_seq_2_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 facet_wrap(vars(grp)) + 
* theme(
* legend.position="none",
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_facets_non_seq_3_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 facet_wrap(vars(grp)) + 
 theme( 
 legend.position="none", 
* strip.background=element_rect(fill="black",color="gray50"),
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_facets_non_seq_4_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 facet_wrap(vars(grp)) + 
 theme( 
 legend.position="none", 
 strip.background=element_rect(fill="black",color="gray50"), 
* strip.text=element_text(
* color="white",face="italic",size=18,
 ), 
* )
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_facets_non_seq_5_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 facet_wrap(vars(grp)) + 
 theme( 
 legend.position="none", 
 strip.background=element_rect(fill="black",color="gray50"), 
 strip.text=element_text( 
 color="white",face="italic",size=18, 
* margin=margin(t=2,b=2,r=2,l=2)
 ), 
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_facets_non_seq_6_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 facet_wrap(vars(grp)) + 
 theme( 
 legend.position="none", 
 strip.background=element_rect(fill="black",color="gray50"), 
 strip.text=element_text( 
 color="white",face="italic",size=18, 
 margin=margin(t=2,b=2,r=2,l=2) 
 ), 
* panel.spacing=unit(0,unit="mm")
 ) 
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/demo_facets_non_seq_7_output-1.png" width="100%" />
]]

---

# Some Help for Remembering All of This

---

.center[
<img src="https://derekogle.com/NCGraphing/modules/zimgs/theme_elements.png" width="99%" />
]

---

# Creating Your Own Theme

---

# Creating Your Own Theme

- Start with an existing theme.
  - i.e., it has most of what you want.

&nbsp;

--
- Add `theme()` to it with the modifications that you want.

&nbsp;

--
- Assign to an object.

&nbsp;

--
- Add this object to a plot when you want to use it.

---

# Creating Your Own Theme

```r
theme_DHO <- theme_bw() +
theme(
 plot.title=element_text(face="bold",size=rel(1.5)),
 axis.title=element_text(face="bold",size=rel(1.25)),
 panel.grid.major=element_line(color="gray90",linetype="dashed",size=rel(0.25)),
 panel.grid.minor=element_blank(),
 legend.margin=margin(t=1,r=1,b=1,l=1,unit="mm"),
 legend.key.size=unit(2,units="mm"),
 panel.spacing=unit(1,unit="mm"),
 strip.background=element_rect(fill="black",color="black"),
 strip.text=element_text(color="white",face="bold",size=rel(1.5),margin=margin(t=1,b=1,r=1,l=1,unit="mm"))
)
```

---

```r
*pb
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/DHO1_auto_1_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
* theme_DHO
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/DHO1_auto_2_output-1.png" width="100%" />
]]

---

```r
*pb
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/DHO2_auto_1_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
* facet_wrap(vars(grp))
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/DHO2_auto_2_output-1.png" width="100%" />
]]
---
class: split-50
count: false

```r
pb + 
 facet_wrap(vars(grp)) + 
* theme_DHO
```
]]
.column[.content[
<img src="Lecture_Themes_files/figure-html/DHO2_auto_3_output-1.png" width="100%" />
]]

---

# Setting a Theme for all Plots

---

# Setting a Theme for all Plots

- It is irritating to always do `theme_bw()` or `theme_DHO`.

&nbsp;

--
- You can set a default theme at the beginning of your session with `theme_set()`, with the name of the theme as the first argument.

--
  - e.g., `theme_set(theme_BW())`
  - e.g., `theme_set(theme_DHO)`
  
---

# Next Time

We will have guest speakers demonstrate case studies.