Base R graphics

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.title[
# Base R graphics
]
.subtitle[
## R Foundations for Data Analysis
]
.author[
### Marcin Kierczak, Nima Rafati
]

---

exclude: true
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---
name: ex1_graphics

# Example graphics

![](data/slide_base_graphics/Life_expectancy_country.png)

Life expectancy.

---
name: ex2_graphics
# Exampel graphics
.pull-left-70[
![](data/slide_base_graphics/Gapminder_GDP.gif)
]
---
name: grapgical_devices
class: spaced

# Graphical devices

The concept of a **graphical device** is crucial for understanding R graphics.

--
A device can be a screen (default) or a file.

Creating a plot entails:  
* opening a graphical device (not necessary for plotting on screen),

--
* plotting to the graphical device,

--
* closing the graphical device (very important!)

# Common graphical devices

<table>
 <thead>
  <tr>
   <th style="text-align:left;"> Device.Type </th>
   <th style="text-align:left;"> Functions </th>
   <th style="text-align:left;"> Notes </th>
  </tr>
 </thead>
<tbody>
  <tr>
   <td style="text-align:left;"> Screen </td>
   <td style="text-align:left;"> default device </td>
   <td style="text-align:left;"> Displays plot on screen </td>
  </tr>
  <tr>
   <td style="text-align:left;"> Bitmap/Raster </td>
   <td style="text-align:left;"> png(), bmp(), tiff(), jpeg() </td>
   <td style="text-align:left;"> Use for images with pixel data </td>
  </tr>
  <tr>
   <td style="text-align:left;"> Vector </td>
   <td style="text-align:left;"> svg(), pdf() </td>
   <td style="text-align:left;"> High-quality, scalable graphics </td>
  </tr>
  <tr>
   <td style="text-align:left;"> Cairo </td>
   <td style="text-align:left;"> cairo_pdf(), cairo_ps() </td>
   <td style="text-align:left;"> Enhanced quality, especially on Windows </td>
  </tr>
</tbody>
</table>

For more information visit [this link](http://stat.ethz.ch/R-manual/R-devel/library/grDevices/html/Devices.html).

---
name: working_with_graphical_devs
class: spaced

# Working with graphical devices

``` r
png(filename = 'myplot.png', width = 320, height = 320, antialias = T)
# anti-aliasing, a technique that smooths the edges of shapes and text in the plot, making them appear less pixelated or jagged.
plot(x=c(1,2,7), y=c(2,3,5))
dev.off()
```

What we did was, in sequence:

* open a graphical device, here `png()` with some parameters,
* do the actual plotting to the device using `plot()` and
* close the graphical device using `dev.off()`.

> It is of paramount importance to remember to close graphical devices. Otherwise, our plots may end up in some random weird files or on screens.

---
name: std_viewport

# Standard graphical device viewport
.pull-left-50[
.size-80[![](data/slide_base_graphics/rmargins_sf.png)]
.small[source: rgraphics.limnology.wisc.edu]
]
--
.pull-right-50[
`c(bottom, left, top, righ)` 
]
---
name: plot_basics

# `base::plot()` basics

`base::plot()` is a basic command that lets you visualize your data and results. It is very powerful yet takes some effort to fully master it. Let's begin with plotting three points:

* A(1,2);
* B(2,3);
* C(7,5);

.size-40[

``` r
plot(x=c(1,2,7), y=c(2,3,5))
```

<img src="slide_base_graphics_files/figure-html/plot1-1.png" width="504" style="display: block; margin: auto;" />
]

---
name: plot_data_frame

# Anatomy of a plot &mdash; episode 1

For convenience, we will create a data frame with our points:

.pull-left-50[

```
##   x y
## A 1 2
## B 2 3
## C 7 5
```
]

.pull-right-50[

``` r
plot(df)
```

<img src="slide_base_graphics_files/figure-html/unnamed-chunk-3-1.png" width="504" style="display: block; margin: auto;" />
]

---
name: plot_anatomy_2

# Anatomy of a plot &mdash; episode 2

.pull-left-50[
There is many parameters one can set in `plot()`. Let's have a closer look at some of them:
* pch &ndash; type of the plotting symbol
* col &ndash; color of the points
* cex &ndash; scale for points
* main &ndash; main title of the plot
* sub &ndash; subtitle of the plot
* xlab &ndash; X-axis label
* ylab &ndash; Y-axis label
* las &ndash; axis labels orientation
* cex.axis &ndash; axis lables scale
* xlim &ndash; X-axis limits or range   
* ylim &ndash; Y-axis limits or range  
]

.pull-right-50[
Let's make our plot a bit fancier...

``` r
# recycling rule in action!
plot(df, pch = c(15, 17, 19), col = c("tomato", "slateblue"), main = "Three points",
    sub = "Stage 1")
```

<img src="slide_base_graphics_files/figure-html/plot2-1.png" width="504" style="display: block; margin: auto;" />
]

---
name: gr_param

# Graphical parameters

Graphical parameters can be set in two different ways:

* as plotting function arguments, e.g. `plot(dat, cex = 0.5)`
* using `par()` to set parameters globally

``` r
# read current graphical parameters
par()
# first, save the current parameters so that you
# can set them back if needed
old_par <- par() # should work in theory, practise varies :-(
# now, modify what you want
par(cex.axis = 0.8, bg='grey')
# do your plotting
plot(................)
# restore the old parameters if you want
par(old_par)
```

---
name: pch_plot

# The `pch` parameter

.size-80[
<img src="slide_base_graphics_files/figure-html/par.pch-1.png" width="504" style="display: block; margin: auto;" />
]

---
name: pch_cheatsheet_code

# How to make the `pch` cheatsheet

``` r
# create a grid of coordinates
coords <- expand.grid(1:6,1:6)
# make a vector of numerical pch symbols
pch.num <- c(0:25)
# and a vector of character pch symbols
pch.symb <- c('*', '.', 'o', 'O', '0', '-', '+', '|', '%', '#')
# plot numerical pch
plot(coords[1:26,1], coords[1:26,2], pch=pch.num,
bty='n', xaxt='n', yaxt='n', bg='red',
xlab='', ylab='')
# and character pch's
points(coords[27:36,1], coords[27:36,2], pch=pch.symb)
# label them
text(coords[,1], coords[,2], c(1:26, pch.symb), pos = 1,
col='slateblue', cex=.8)
```
> Now, make your own cheatsheet for the **lty** parameter!

---
name: layers_1

# Layers

Elements are added to a plot in the same order you plot them.
It is like layers in a graphical program. Think about it! For instance the auxiliary grid lines should be plotted before the actual data points.

.pull-left-50[

``` r
# make an empty plot
plot(1:5, type = "n", las = 1, bty = "n")
grid(col = "grey", lty = 3)
points(1:5, pch = 19, cex = 3)
abline(h = 3, col = "red")
```
]
.pull-right-50[
<img src="slide_base_graphics_files/figure-html/gr.layers.ex-1.png" width="504" style="display: block; margin: auto;" />
]
The line overlaps one data point. It is better to plot it before plotting `points()`

---
name: general_thoughts
class: spaced

# Some thoughts about plotting

There is a few points you should have in mind when working with plots:

--
* raster or vector graphics,

--
* colors, e.g. color-blind people, warm vs. cool colors and optical illusions (check [colorbrewer2.org](https://colorbrewer2.org/#type=sequential&scheme=BuGn&n=3)),

--
* avoid complications, e.g. 3D plots, pie charts etc.,

--
* use black and shades of grey for things you do not need to emphasize, i.e. basically everything except your main result,

--
* avoid 3 axes on one figure.

---
name: many_plots_on_one_fig

# Many plots on one figure

.pull-left-40[

``` r
par(mfrow=c(2,3))
plot(1:5)
plot(1:5, pch=19, col='red')
plot(1:5, pch=15, col='blue')
hist(rnorm(100, mean = 0, sd=1))
hist(rnorm(100, mean = 7, sd=3))
hist(rnorm(100, mean = 1, sd=0.5))
par(mfrow=c(1,1))
```
Alternative: use `par(mfcol=c(3,2))`.
]

.pull-right-60[
<img src="slide_base_graphics_files/figure-html/mfrow.ex-1.png" width="504" style="display: block; margin: auto;" />
]

---
name: layout

# Using `graphics::layout()`

.pull-left-50[

``` r
M <- matrix(c(1,2,2,2,3,2,2,2), nrow = 2, ncol = 4, byrow = T)
M
layout(mat = M)
layout.show(n = 3) #It shows the layout setup without plots
```

```
##      [,1] [,2] [,3] [,4]
## [1,]    1    2    2    2
## [2,]    3    2    2    2
```
]

.pull-right-50[

``` r
M <- matrix(c(1,2,2,2,3,2,2,2), nrow = 2, ncol = 4, byrow = T)
layout(mat = M)
plot(1:5, pch=15, col='blue')
hist(rnorm(100, mean = 0, sd=1))
plot(1:5, pch=15, col='red')
```

<img src="slide_base_graphics_files/figure-html/layout_ex-1.png" width="504" style="display: block; margin: auto;" />
]

---
name: colors

# Defining colors

``` r
mycol <- c(rgb(0, 0, 1), "olivedrab", "#FF0000")
plot(1:3, c(1, 1, 1), col = mycol, pch = 19, cex = 3)
points(2, 1, col = rgb(0, 0, 1, 0.5), pch = 15, cex = 5)
```

--
<img src="slide_base_graphics_files/figure-html/color_ex-1.png" width="360" style="display: block; margin: auto;" />

---
name: palettes

# Color palettes

There some built-in palettes: default, hsv, gray, rainbow, terrain.colors, topo.colors, cm.colors, heat.colors

``` r
mypal <- heat.colors(10)
mypal
pie(x = rep(1, times = 10), col = mypal)
```

```
##  [1] "#FF0000" "#FF2400" "#FF4900" "#FF6D00" "#FF9200" "#FFB600" "#FFDB00"
##  [8] "#FFFF00" "#FFFF40" "#FFFFBF"
```

---
name: custom_palettes

# Custom color palettes

.pull-left-50[
You can easily create custom palettes:

``` r
mypal <- colorRampPalette(c("red", "green", "blue"))
pie(x = rep(1, times = 12), col = mypal(12))
class(mypal)
```

```
## [1] "function"
```

<img src="slide_base_graphics_files/figure-html/color.pal.custom-1.png" width="504" style="display: block; margin: auto;" />
]

.pull-right-50[
> **Note:**`grDevices::colorRampPalette()` returns a function for generating colors based on the defined custom palette!

> There is an excellent package `RColorBrewer` that offers a number of pre-made palettes, e.g. color-blind safe palette.

> Package `wesanderson` offers palettes based on Wes Anderson's movies :-)
]

---
name: boxplot_theory

# Box-and-whiskers plot &mdash; theory

There are also more specialized R functions used for creating specific types of plots. One commonly used is `graphics::boxplot()`
.size-40[.center[![](data/slide_base_graphics/wiki_boxplot.png)]]

> **Rule of thumb.** If median of one boxplot is outside the box of another, the median difference is likely to be significant `\(\alpha = 5\%\)`.

---
name: boxplot

# Box-and-whiskers plot

.pull-left-50[

``` r
boxplot(decrease ~ treatment,
data = OrchardSprays,
log = "y", col = "bisque",
varwidth=TRUE)
```

<img src="slide_base_graphics_files/figure-html/boxplot-1.png" width="504" style="display: block; margin: auto;" />
]

.pull-right-50[
The `add=TRUE` parameter in plots allows you to compose plots using previously plotted stuff!

``` r
attach(InsectSprays)
boxplot(count~spray, data=InsectSprays[spray %in% c("C","F"),], col="lightgray")
boxplot(count~spray, data=InsectSprays[spray %in% c("A","B"),], col="tomato", add=TRUE)
boxplot(count~spray, data=InsectSprays[spray %in% c("D","E"),], col="slateblue", add=TRUE)
detach(InsectSprays)
```

<img src="slide_base_graphics_files/figure-html/boxplot2-1.png" width="288" style="display: block; margin: auto;" />
]

---
name: vcd

# Plotting categorical data

``` r
data(Titanic) # Load the data
vcd::mosaic(Titanic,
            labeling = vcd::labeling_border(rot_labels = c(0,0,0,0)))
```

<img src="slide_base_graphics_files/figure-html/vcd.titanic-1.png" width="432" style="display: block; margin: auto;" />
> Package `vcd` provides a lot of ways of visualizing categorical data.

---
name: heatmaps

# Plotting simple heatmaps

``` r
heatmap(matrix(rnorm(100, mean = 0, sd = 1), nrow = 10),
col=terrain.colors(10))
```

---
name: graph_gallery

# Graph gallery

For more awesome examples visit: [http://www.r-graph-gallery.com](http://www.r-graph-gallery.com)

![](data/slide_base_graphics/graph_gallery.png)

---
name: end_slide
class: end-slide, middle
count: false

# Thank you! Questions?

.end-text[
<p class="smaller">
<span class="small" style="line-height: 1.2;">Graphics from </span><img src="./assets/freepik.jpg" style="max-height:20px; vertical-align:middle;"><br>
Created: 31-Oct-2024 • <a href="https://www.scilifelab.se/">SciLifeLab</a> • <a href="https://nbis.se/">NBIS</a> 
</p>
]