lab-gapminder

L3 MIASHS
Université Paris Cité
Année 2023-2024
Course Homepage
Moodle

We will use the following packages. If needed, we install them.

Code

to_be_loaded <- c("tidyverse", 
                  "patchwork", 
                  "glue", 
                  "ggforce", 
                  "plotly",
                  "ggthemes",
                  "gapminder",
                  "ggrepel")

for (pck in to_be_loaded) {
  if (!require(pck, character.only = T)) {
    install.packages(pck, repos="http://cran.rstudio.com/")
    stopifnot(require(pck, character.only = T))
  }  
}

Grammar of Graphics

We will use the Grammar of Graphics approach to visualization

The expression Grammar of Graphics was coined by Leiland Wilkinson to describe a principled approach to visualization in Data Analysis (EDA)

A plot is organized around data (a table with rows (observations) and columns (variables))

A plot is a graphical object that can be built layer by layer

Building a graphical object consists in chaining elementary operations

The acclaimed TED presentation by Hans Rosling illustrates the Grammar of Graphics approach

Code

knitr::include_url("https://www.youtube.com/embed/jbkSRLYSojo")

We will reproduce the animated demonstration using

ggplot2: an implementation of grammar of graphics in `R
plotly: a bridge between R and the javascript library D3.js
Using plotly, opting for html ouput, brings the possibility of interactivity and animation

Install and load packages

Code

require("gapminder")

Insist on the difference between installing and loading a package

How do we get the list of installed packages?
How do we get the list of loaded packages?
Which objects are made available by a package?

solution

The (usually very long) list of installed packages can be obtained by a simple function call.

Code

df <- installed.packages()
head(df)
##               Package        
## addinexamples "addinexamples"
## alphavantager "alphavantager"
## anytime       "anytime"      
## arrow         "arrow"        
## askpass       "askpass"      
## assertthat    "assertthat"   
##               LibPath                                             Version   
## addinexamples "/home/boucheron/R/x86_64-pc-linux-gnu-library/4.1" "0.1.0"   
## alphavantager "/home/boucheron/R/x86_64-pc-linux-gnu-library/4.1" "0.1.3"   
## anytime       "/home/boucheron/R/x86_64-pc-linux-gnu-library/4.1" "0.3.9"   
## arrow         "/home/boucheron/R/x86_64-pc-linux-gnu-library/4.1" "13.0.0.1"
## askpass       "/home/boucheron/R/x86_64-pc-linux-gnu-library/4.1" "1.2.0"   
## assertthat    "/home/boucheron/R/x86_64-pc-linux-gnu-library/4.1" "0.2.1"   
##               Priority Depends       
## addinexamples NA       "R (>= 3.0.0)"
## alphavantager NA       "R (>= 3.3.0)"
## anytime       NA       "R (>= 3.2.0)"
## arrow         NA       "R (>= 3.4)"  
## askpass       NA       NA            
## assertthat    NA       NA            
##               Imports                                                                                                                                                                                       
## addinexamples "shiny (>= 0.13), miniUI (>= 0.1.1), rstudioapi (>= 0.4),\nformatR"                                                                                                                           
## alphavantager "dplyr (>= 0.7.0), glue (>= 1.1.1), httr (>= 1.2.1), jsonlite\n(>= 1.5), purrr (>= 0.2.2.2), readr (>= 1.1.1), stringr (>=\n1.2.0), tibble (>= 1.3.3), tidyr (>= 0.6.3), timetk (>=\n0.1.1.1)"
## anytime       "Rcpp (>= 0.12.9)"                                                                                                                                                                            
## arrow         "assertthat, bit64 (>= 0.9-7), glue, methods, purrr, R6, rlang\n(>= 1.0.0), stats, tidyselect (>= 1.0.0), utils, vctrs"                                                                       
## askpass       "sys (>= 2.1)"                                                                                                                                                                                
## assertthat    "tools"                                                                                                                                                                                       
##               LinkingTo             
## addinexamples NA                    
## alphavantager NA                    
## anytime       "Rcpp (>= 0.12.9), BH"
## arrow         "cpp11 (>= 0.4.2)"    
## askpass       NA                    
## assertthat    NA                    
##               Suggests                                                                                                                                                                                                      
## addinexamples NA                                                                                                                                                                                                            
## alphavantager "testthat, knitr"                                                                                                                                                                                             
## anytime       "tinytest (>= 1.0.0), gettz"                                                                                                                                                                                  
## arrow         "blob, cli, DBI, dbplyr, decor, distro, dplyr, duckdb (>=\n0.2.8), hms, jsonlite, knitr, lubridate, pillar, pkgload,\nreticulate, rmarkdown, stringi, stringr, sys, testthat (>=\n3.1.0), tibble, tzdb, withr"
## askpass       "testthat"                                                                                                                                                                                                    
## assertthat    "testthat, covr"                                                                                                                                                                                              
##               Enhances License                   License_is_FOSS
## addinexamples NA       "MIT + file LICENSE"      NA             
## alphavantager NA       "GPL (>= 3)"              NA             
## anytime       NA       "GPL (>= 2)"              NA             
## arrow         NA       "Apache License (>= 2.0)" NA             
## askpass       NA       "MIT + file LICENSE"      NA             
## assertthat    NA       "GPL-3"                   NA             
##               License_restricts_use OS_type MD5sum NeedsCompilation Built  
## addinexamples NA                    NA      NA     "no"             "4.1.2"
## alphavantager NA                    NA      NA     "no"             "4.1.2"
## anytime       NA                    NA      NA     "yes"            "4.1.2"
## arrow         NA                    NA      NA     "yes"            "4.1.2"
## askpass       NA                    NA      NA     "yes"            "4.1.2"
## assertthat    NA                    NA      NA     "no"             "4.1.2"

Note that the output is tabular (it is a matrix and an array) that contains much more than the names of installed packages. If we just want the names of the installed packages, we can extract the column named Package.

Code

df[1:5, c("Package", "Version") ]
##               Package         Version   
## addinexamples "addinexamples" "0.1.0"   
## alphavantager "alphavantager" "0.1.3"   
## anytime       "anytime"       "0.3.9"   
## arrow         "arrow"         "13.0.0.1"
## askpass       "askpass"       "1.2.0"

Matrices and arrays represent mathematical object and are fit for computations. They are not so convenient as far as querying is concerned. Dataframes which are also tabular objects can be queried like tables in a relational database.

Loading a package amounts to make a number of objects available in the current session. The objects are made available though Namespaces.

Code

loadedNamespaces()
##  [1] "tidyselect"  "xfun"        "purrr"       "ggthemes"    "colorspace" 
##  [6] "vctrs"       "generics"    "htmltools"   "viridisLite" "yaml"       
## [11] "grDevices"   "utf8"        "plotly"      "rlang"       "pillar"     
## [16] "glue"        "withr"       "tidyverse"   "tweenr"      "lifecycle"  
## [21] "stringr"     "munsell"     "gtable"      "htmlwidgets" "evaluate"   
## [26] "knitr"       "forcats"     "tzdb"        "fastmap"     "gapminder"  
## [31] "fansi"       "highr"       "methods"     "Rcpp"        "readr"      
## [36] "scales"      "jsonlite"    "farver"      "ggforce"     "ggplot2"    
## [41] "stats"       "datasets"    "graphics"    "hms"         "digest"     
## [46] "stringi"     "ggrepel"     "dplyr"       "polyclip"    "grid"       
## [51] "cli"         "tools"       "magrittr"    "lazyeval"    "patchwork"  
## [56] "tibble"      "tidyr"       "pkgconfig"   "MASS"        "data.table" 
## [61] "utils"       "lubridate"   "timechange"  "rmarkdown"   "base"       
## [66] "httr"        "rstudioapi"  "R6"          "compiler"

Note that we did not load explicitly some of the loadedNamespaces.

Code

setdiff(loadedNamespaces(), to_be_loaded)
##  [1] "tidyselect"  "xfun"        "purrr"       "colorspace"  "vctrs"      
##  [6] "generics"    "htmltools"   "viridisLite" "yaml"        "grDevices"  
## [11] "utf8"        "rlang"       "pillar"      "withr"       "tweenr"     
## [16] "lifecycle"   "stringr"     "munsell"     "gtable"      "htmlwidgets"
## [21] "evaluate"    "knitr"       "forcats"     "tzdb"        "fastmap"    
## [26] "fansi"       "highr"       "methods"     "Rcpp"        "readr"      
## [31] "scales"      "jsonlite"    "farver"      "ggplot2"     "stats"      
## [36] "datasets"    "graphics"    "hms"         "digest"      "stringi"    
## [41] "dplyr"       "polyclip"    "grid"        "cli"         "tools"      
## [46] "magrittr"    "lazyeval"    "tibble"      "tidyr"       "pkgconfig"  
## [51] "MASS"        "data.table"  "utils"       "lubridate"   "timechange" 
## [56] "rmarkdown"   "base"        "httr"        "rstudioapi"  "R6"         
## [61] "compiler"

Many of the loaded packages were loaded while loading other packages, for example metapackages like tidyverse.

Have a look at `gapminder` dataset

A table has a schema: a list of named columns, each with a given type
A table has a content: rows. Each row is a collection of items, corresponding to the columns
glimpse() allows to see the schema and the first rows
head() allows to see the first rows

solution

Dataframes

Code

gapminder <- gapminder::gapminder

glimpse(gapminder)
## Rows: 1,704
## Columns: 6
## $ country   <fct> "Afghanistan", "Afghanistan", "Afghanistan", "Afghanistan", …
## $ continent <fct> Asia, Asia, Asia, Asia, Asia, Asia, Asia, Asia, Asia, Asia, …
## $ year      <int> 1952, 1957, 1962, 1967, 1972, 1977, 1982, 1987, 1992, 1997, …
## $ lifeExp   <dbl> 28.801, 30.332, 31.997, 34.020, 36.088, 38.438, 39.854, 40.8…
## $ pop       <int> 8425333, 9240934, 10267083, 11537966, 13079460, 14880372, 12…
## $ gdpPercap <dbl> 779.4453, 820.8530, 853.1007, 836.1971, 739.9811, 786.1134, …

gapminder %>%  
  glimpse()
## Rows: 1,704
## Columns: 6
## $ country   <fct> "Afghanistan", "Afghanistan", "Afghanistan", "Afghanistan", …
## $ continent <fct> Asia, Asia, Asia, Asia, Asia, Asia, Asia, Asia, Asia, Asia, …
## $ year      <int> 1952, 1957, 1962, 1967, 1972, 1977, 1982, 1987, 1992, 1997, …
## $ lifeExp   <dbl> 28.801, 30.332, 31.997, 34.020, 36.088, 38.438, 39.854, 40.8…
## $ pop       <int> 8425333, 9240934, 10267083, 11537966, 13079460, 14880372, 12…
## $ gdpPercap <dbl> 779.4453, 820.8530, 853.1007, 836.1971, 739.9811, 786.1134, …

gapminder %>% 
  head()
## # A tibble: 6 × 6
##   country     continent  year lifeExp      pop gdpPercap
##   <fct>       <fct>     <int>   <dbl>    <int>     <dbl>
## 1 Afghanistan Asia       1952    28.8  8425333      779.
## 2 Afghanistan Asia       1957    30.3  9240934      821.
## 3 Afghanistan Asia       1962    32.0 10267083      853.
## 4 Afghanistan Asia       1967    34.0 11537966      836.
## 5 Afghanistan Asia       1972    36.1 13079460      740.
## 6 Afghanistan Asia       1977    38.4 14880372      786.

Even an empty dataframe has a scheme:

Code

gapminder %>% 
  head(0) %>% 
  glimpse()

Rows: 0
Columns: 6
$ country   <fct> 
$ continent <fct> 
$ year      <int> 
$ lifeExp   <dbl> 
$ pop       <int> 
$ gdpPercap <dbl>

Code

glimpse(head(gapminder, 0))

Rows: 0
Columns: 6
$ country   <fct> 
$ continent <fct> 
$ year      <int> 
$ lifeExp   <dbl> 
$ pop       <int> 
$ gdpPercap <dbl>

solution

The schema of a dataframe/tibble is the list of column names and classes. The content of a dataframe is made of the rows. A dataframe may have null content

Code

gapminder %>% 
  filter(FALSE) %>% 
  glimpse()
## Rows: 0
## Columns: 6
## $ country   <fct> 
## $ continent <fct> 
## $ year      <int> 
## $ lifeExp   <dbl> 
## $ pop       <int> 
## $ gdpPercap <dbl>

Get a feeling of the dataset

Pick two random rows for each continent using slice_sample()

solution

To pick a slice at random, we can use function slice_sample. We can even perform sampling within groups defined by the value of a column.

Code

gapminder %>% 
  slice_sample(n=2, by=continent)

# A tibble: 10 × 6
   country         continent  year lifeExp      pop gdpPercap
   <fct>           <fct>     <int>   <dbl>    <int>     <dbl>
 1 Afghanistan     Asia       1962    32.0 10267083      853.
 2 Taiwan          Asia       1962    65.2 11918938     1823.
 3 Montenegro      Europe     1992    75.4   621621     7003.
 4 Slovak Republic Europe     1977    70.4  4827803    10923.
 5 Congo, Rep.     Africa     1977    55.6  1536769     3259.
 6 Cote d'Ivoire   Africa     1967    47.4  4744870     2052.
 7 Nicaragua       Americas   1957    45.4  1358828     3457.
 8 Peru            Americas   2007    71.4 28674757     7409.
 9 New Zealand     Oceania    1972    71.9  2929100    16046.
10 Australia       Oceania    1957    70.3  9712569    10950.

Code

#< or equivalently 
gapminder %>% 
  group_by(continent) %>% 
  slice_sample(n=2)

# A tibble: 10 × 6
# Groups:   continent [5]
   country               continent  year lifeExp      pop gdpPercap
   <fct>                 <fct>     <int>   <dbl>    <int>     <dbl>
 1 Liberia               Africa     2002    43.8  2814651      531.
 2 Sao Tome and Principe Africa     1997    63.3   145608     1339.
 3 Haiti                 Americas   1972    48.0  4698301     1654.
 4 Chile                 Americas   1982    70.6 11487112     5096.
 5 Nepal                 Asia       1992    55.7 20326209      898.
 6 Myanmar               Asia       1997    60.3 43247867      415 
 7 Denmark               Europe     1967    73.0  4838800    15937.
 8 Iceland               Europe     1977    76.1   221823    19655.
 9 New Zealand           Oceania    1977    72.2  3164900    16234.
10 New Zealand           Oceania    2002    79.1  3908037    23190.

What makes a table tidy?

Have a look at Data tidying in R for Data Science (2nd ed.)

Is the gapminder table redundant?

solution

gapminder is redundant: column country completely determines the content of column continent. In database parlance, we have a functional dependancy: country → continent whereas the key of the table is made of columns country, year.

Table gapminder is not in Boyce-Codd Normal Form (BCNF), not even in Third Normal Form (3NF).

Gapminder tibble (extract)

Extract/filter a subset of rows using dplyr::filter(...)

solution

Code

gapminder %>% 
  filter(country=='France') %>% 
  head()

# A tibble: 6 × 6
  country continent  year lifeExp      pop gdpPercap
  <fct>   <fct>     <int>   <dbl>    <int>     <dbl>
1 France  Europe     1952    67.4 42459667     7030.
2 France  Europe     1957    68.9 44310863     8663.
3 France  Europe     1962    70.5 47124000    10560.
4 France  Europe     1967    71.6 49569000    13000.
5 France  Europe     1972    72.4 51732000    16107.
6 France  Europe     1977    73.8 53165019    18293.

Note that equality testing is performed using == not = (which is used to implement assignment)

Filtering (selection $σ$ from database theory) : Picking one year of data

There is simple way to filter rows satisfying some condition. It consists in mimicking indexation in a matrix, leaving the colum index empty, replacing the row index by a condition statement (a logical expression) also called a mask.

Code

gapminder_2002 <- gapminder[gapminder$year==2002, ]

Have a look at gapminder$year==2002. What is the type/class of this expression?

This is possible in base R and very often convenient.

Nevertheless, this way of performing row filtering does not emphasize the connection between the dataframe and the condition. Any logical vector with the right length could be used as a mask. Moreover, this way of performing filtering is not very functional.

In the parlance of Relational Algebra, filter performs a selection of rows. Relational expression \[σ_{\text{condition}}(\text{Table})\] translates to

Code

filter(Table, condition)

where $\text{condition}$ is a boolean expression that can be evaluated on each row of $\text{Table}$. In SQL, the relational expression would translate into

SELECT *
FROM Table
WHERE condition

Check Package dplyr docs

The posit cheatsheet on dplyr is an unvaluable resource for table manipulation.

Use dplyr::filter() to perform row filtering

solution

Code

# filter(gapminder, year==2002)

gapminder %>% 
  filter(year==2002)

# A tibble: 142 × 6
   country     continent  year lifeExp       pop gdpPercap
   <fct>       <fct>     <int>   <dbl>     <int>     <dbl>
 1 Afghanistan Asia       2002    42.1  25268405      727.
 2 Albania     Europe     2002    75.7   3508512     4604.
 3 Algeria     Africa     2002    71.0  31287142     5288.
 4 Angola      Africa     2002    41.0  10866106     2773.
 5 Argentina   Americas   2002    74.3  38331121     8798.
 6 Australia   Oceania    2002    80.4  19546792    30688.
 7 Austria     Europe     2002    79.0   8148312    32418.
 8 Bahrain     Asia       2002    74.8    656397    23404.
 9 Bangladesh  Asia       2002    62.0 135656790     1136.
10 Belgium     Europe     2002    78.3  10311970    30486.
# ℹ 132 more rows

Note that in stating the condition, we simply write year==2002 even though year is not the name of an object in our current session. This is possible because filter( ) uses data masking, year is meant to denote a column in gapminder.

The ability to use data masking is one of the great strengths of the R programming language.

Static plotting: First attempt

Define a plot with respect to gapminder_2002

solution

Code

p <- gapminder_2002 %>%
  ggplot()

You should define a ggplot object with data layer gapminder_2022 and call this object p for further reuse.

Map variables gdpPercap and lifeExp to axes x and y

solution

Code

p <- p +
  aes(x=gdpPercap, y=lifeExp)
p

Use ggplot object p and add a global aesthetic mapping gdpPercap and lifeExp to axes x and y (using + from ggplot2) .

For each row, draw a point at coordinates defined by the mapping

solution

Code

p +
  geom_point()

You need to add a geom_ layer to your ggplot object, in this case geom_point() will do.

We are building a graphical object (a ggplot object) around a data frame (gapminder)

We supply aesthetic mappings (aes()) that can be either global or bound to some geometries (geom_point())or statistics

The global aesthetic mapping defines which columns are

mapped to which axes,
possibly mapped to colours, linetypes, shapes, …

Geometries and Statistics describe the building blocks of graphics

What’s missing here?

when comparing to the Gapminder demonstration, we can spot that

colors are missing
bubble sizes are all the same. They should reflect the population size of the country
titles and legends are missing. This means the graphic object is useless.

We will add layers to the graphical object to complete the plot

Second attempt: display more information

Map continent to color (use aes())
Map pop to bubble size (use aes())
Make point transparent by tuning alpha (inside geom_point() avoid overplotting)

solution

Code

p <- p +
  aes(color=continent, size=pop) +
  geom_point(alpha=.5) 

p

solution

In this enrichment of the graphical object, guides have been automatically added for two aesthetics: color and size. Those two guides are deemed necessary since the reader has no way to guess the mapping from the five levels of continent to color (the color scale), and the reader needs help to connect population size and bubble size.

ggplot2 provides us with helpers to fine tune guides.

The scalings on the x and y axis do not deserve guides: the ticks along the coordinate axes provide enough information.

Scaling

In order to pay tribute to Hans Rosling, we need to take care of two scaling issues:

the gdp per capita axis should be logarithmic scale_x_log10()
the area of the point should be proportional to the population scale_size_area()

solution

Code

p <- p +
  scale_x_log10() +
  scale_size_area()

p

Motivate the proposed scalings.

Why is it important to use logarithmic scaling for gdp per capita?
When is it important to use logarithmic scaling on some axis (in other contexts)?
Why is it important to specify scale_size_area() ?

solution

Code

p +
  scale_radius()

Scale for size is already present.
Adding another scale for size, which will replace the existing scale.

solution

Code

ptchwrk <- (p + ggtitle("scale_size_area")) + (p + scale_size() + ggtitle("scale"))

Scale for size is already present.
Adding another scale for size, which will replace the existing scale.

Code

ptchwrk + plot_annotation(
  title='Comparing scale_size_area and scale_size', 
  caption='In the current setting, scale_size_area() should be favored'
)

In perspective

Add a plot title
Make axes titles
- explicit
- readable
Use labs(...)

solution

Code

yoi <- 2002

p <-  p + 
  labs(
    title=glue('The world in year {yoi}'),
    x="Gross Domestic Product per capita (US$ 2009, corrected for PPP)",
    y="Life expectancy at birth"
  )

p

solution

We should also fine tune the guides: replace pop by Population and titlecase continent.

What should be the respective purposes of Title, Subtitle, Caption, … ?

Theming using `ggthemes` (or not)

Theming

Code

require("ggthemes")

Look at the online help on pacman::p_load(), how does pacman::p_load() relate to require() and library()?

A theme defines the look and feel of plots

Within a single document, we should use only one theme

See Getting the theme for a gallery of available themes

Code

p +
  theme_economist()

Tuning scales

Use scale_color_manual(...) to hand-tune the color aesthetic mapping.

Code

```{r}
#| label: theme_scale
neat_color_scale <-
      c("Africa" = "#01d4e5",
        "Americas" = "#7dea01" ,
        "Asia" = "#fc5173",
        "Europe" = "#fde803",
        "Oceania" = "#536227")
```

solution

Code

p <- p +
  scale_size_area(max_size = 15) + #<<
  scale_color_manual(values = neat_color_scale) #<<

Scale for size is already present.
Adding another scale for size, which will replace the existing scale.

Code

Choosing a color scale is a difficult task

viridis is often a good pick.

solution

Mimnimalist themes are often a good pick.

Code

old_theme <- theme_set(theme_minimal())

Code

p <- p +
   scale_size_area(max_size = 15,
                  labels= scales::label_number(scale=1/1e6,
                                               suffix=" M")) +
   scale_color_manual(values = neat_color_scale) +
    labs(title= glue("Gapminder  {min(gapminder$year)}-{max(gapminder$year)}"),
         x = "Yearly Income per Capita",
         y = "Life Expectancy",
       caption="From sick  and poor (bottom left) to healthy and rich (top right)")

Scale for size is already present.
Adding another scale for size, which will replace the existing scale.
Scale for colour is already present.
Adding another scale for colour, which will replace the existing scale.

Code

p + theme(legend.position = "none")

Adding labels

solution

Code

require(ggrepel) #<<
 
p +
   aes(label=country) + #<<
   ggrepel::geom_label_repel(max.overlaps = 5) + #<<
   scale_size_area(max_size = 15,
                  labels= scales::label_number(scale=1/1e6,
                                               suffix=" M")) +
   scale_color_manual(values = neat_color_scale) +
   theme(legend.position = "none") +
    labs(title= glue("Gapminder  {min(gapminder$year)}-{max(gapminder$year)}"),
         x = "Yearly Income per Capita",
         y = "Life Expectancy",
       caption="From sick  and poor (bottom left) to healthy and rich (top right)")

Animate for free with `plotly`

Use plotly::ggplotly()

solution

Code

```{r}
#| label: animate
#| eval: !expr knitr::is_html_output()
#| code-annotations: hover

q <- filter(gapminder, FALSE) %>%
   ggplot() +
   aes(x = gdpPercap) +
   aes(y = lifeExp) +
   aes(size = pop) +
   aes(text = country) +                   #
   aes(fill = continent) +
   # aes(frame = year) +                     #
  geom_point(alpha=.5, colour='black') +
  scale_x_log10() +
  scale_size_area(max_size = 15,
                  labels= scales::label_number(scale=1/1e6,
                                               suffix=" M")) +
  scale_fill_manual(values = neat_color_scale) +
  theme(legend.position = "none") +
  labs(title= glue("Gapminder  {min(gapminder$year)}-{max(gapminder$year)}"),
       x = "Yearly Income per Capita",
       y = "Life Expectancy",
       caption="From sick  and poor (bottom left) to healthy and rich (top right)")


(q %+% gapminder) %>%
  plotly::ggplotly(height = 500, width=750)   
```

text will be used while hovering
frame is used by plotly to drive the animation. One frame per year

solution

Code

```{r}
#| eval: !expr knitr::is_html_output()

(p %+% gapminder +
 facet_null() +
 aes(frame=year)) %>%
 plotly::ggplotly(height = 500, width=750)
```

More material

Read Visualization in R for Data Science

Grammar of Graphics

Install and load packages

Have a look at gapminder dataset

Get a feeling of the dataset

Gapminder tibble (extract)

Filtering (selection \(σ\) from database theory) : Picking one year of data

Static plotting: First attempt

What’s missing here?

Second attempt: display more information

Scaling

In perspective

Theming using ggthemes (or not)

Tuning scales

Adding labels

Animate for free with plotly

More material

Have a look at `gapminder` dataset

Theming using `ggthemes` (or not)

Animate for free with `plotly`