Antarctic Sea ice

1 Setting up R Packages

Plot Fonts and Theme

Show the Code
library(systemfonts)
library(showtext)
## Clean the slate
systemfonts::clear_local_fonts()
systemfonts::clear_registry()
##
showtext_opts(dpi = 96) # set DPI for showtext
sysfonts::font_add(
  family = "Alegreya",
  regular = "../../../../../../fonts/Alegreya-Regular.ttf",
  bold = "../../../../../../fonts/Alegreya-Bold.ttf",
  italic = "../../../../../../fonts/Alegreya-Italic.ttf",
  bolditalic = "../../../../../../fonts/Alegreya-BoldItalic.ttf"
)

sysfonts::font_add(
  family = "Roboto Condensed",
  regular = "../../../../../../fonts/RobotoCondensed-Regular.ttf",
  bold = "../../../../../../fonts/RobotoCondensed-Bold.ttf",
  italic = "../../../../../../fonts/RobotoCondensed-Italic.ttf",
  bolditalic = "../../../../../../fonts/RobotoCondensed-BoldItalic.ttf"
)
showtext_auto(enable = TRUE) # enable showtext
##
theme_custom <- function() {
  font <- "Alegreya" # assign font family up front
  "%+replace%" <- ggplot2::"%+replace%" # nolint

  theme_classic(base_size = 14, base_family = font) %+replace% # replace elements we want to change

    theme(
      text = element_text(family = font), # set base font family

      # text elements
      plot.title = element_text( # title
        family = font, # set font family
        size = 24, # set font size
        face = "bold", # bold typeface
        hjust = 0, # left align
        margin = margin(t = 5, r = 0, b = 5, l = 0)
      ), # margin
      plot.title.position = "plot",
      plot.subtitle = element_text( # subtitle
        family = font, # font family
        size = 14, # font size
        hjust = 0, # left align
        margin = margin(t = 5, r = 0, b = 10, l = 0)
      ), # margin

      plot.caption = element_text( # caption
        family = font, # font family
        size = 9, # font size
        hjust = 1
      ), # right align

      plot.caption.position = "plot", # right align

      axis.title = element_text( # axis titles
        family = "Roboto Condensed", # font family
        size = 12
      ), # font size

      axis.text = element_text( # axis text
        family = "Roboto Condensed", # font family
        size = 9
      ), # font size

      axis.text.x = element_text( # margin for axis text
        margin = margin(5, b = 10)
      )

      # since the legend often requires manual tweaking
      # based on plot content, don't define it here
    )
}

## Use available fonts in ggplot text geoms too!
ggplot2::update_geom_defaults(geom = "text", new = list(
  family = "Roboto Condensed",
  face = "plain",
  size = 3.5,
  color = "#2b2b2b"
))

## Set the theme
ggplot2::theme_set(new = theme_custom())

2 Introduction

The extent of Antarctic Sea Ice over time is monitored by the National Snow and Ice Data Center https://nsidc.org/.

3 Read the Data

NoteExcel Data

The data is an excel sheet. Inspect it first in Excel and decide which sheet you need, and which part of the data you need. There are multiple sheets! Then use readxl::read_xlsx(..) to read it into R. NOTE: The sheet that contains our data of interest is titled “SH-Daily-Extent”.

4 Inspect the Data

Appreciate the structure of this data. You may even want to open it in Excel for a closer look. List any imperfections in your Data Dictionary. Why do these matter now? Why might they not have mattered earlier, up to now?

5 Data Dictionary

NoteQuantitative Variables

Write in.

NoteQualitative Variables

Write in.

NoteObservations

Write in.

6 Analyse/Transform the Data

Try to figure what may be needed, based on the imperfections noted above, what you may attempt to clean the data. Refer to your “list of imperfections” in the data.

Then look at the code below and execute line by line to get an idea.

```{r}
#| label: data-preprocessing
#
# Write in your code here
# to prepare this data as shown below
# to generate the plot that follows
```
Show the Code
ice %>%
  # Select columns
  # Rename some while selecting !!
  select("month" = ...1, "day" = ...2, c(4:49)) %>%
  # Fill the month column! Yes!!
  tidyr::fill(month) %>%
  # Make Wide Data into Long
  pivot_longer(
    cols = -c(month, day),
    names_to = "series",
    values_to = "values"
  ) %>%
  # Regular Munging
  mutate(
    series = as.integer(series),
    month = factor(month,
      levels = month.name,
      labels = month.name,
      ordered = TRUE
    ),
    # Note munging for date!!
    # Using the lubridate package, part of tidyverse
    date = lubridate::make_date(
      year = series,
      month = month,
      day = day
    )
  ) -> ice_prepared

ice_prepared

7 Research Question

Note

Write in! Look first at the graph!

8 Plot the Data

Error in `position_dodge()`:
! `orientation` must be a string or character vector.

9 Tasks and Discussion

  • Complete the Data Dictionary.
  • Select and Transform the variables as shown.
  • Create the graphs shown and discuss the following questions:
    • Identify the type of charts
    • Identify the variables used for various geometrical aspects (x, y, fill…). Name the variables appropriately.
    • What research activity might have been carried out to obtain the data graphed here? Provide some details.
    • What might have been the Hypothesis/Research Question to which the response was Chart?
    • What might the red points represent?
    • What is perhaps a befuddling aspect of this graph until you…Ohhh!!!!!!
    • Draw a sketch of a similar chart for ice extents in the Arctic.
Back to top