14  Mid-semester review

TipSETTLING IN

You won’t type anything today! For future reference you can access the following:



NoteLearning goals

Review the basics of wrangling and visualization

14.1 Warm-up

Recall the major themes of our work thus far:

  • Getting to know your data
    • key functions: head(), dim(), nrow(), class(), str()


  • Data visualization
    • picking an appropriate plot / evaluating the appropriateness of a plot
    • interpreting the results of a plot
    • building effective plots that are accessible and “professional”
    • key functions:
      • ggplot()
      • geom_bar(), geom_density(), geom_boxplot(), geom_histogram(), geom_point(), geom_line(), geom_smooth()
      • facet_wrap()
    • key features:
      • color, fill
      • fig.alt, fig.caption


  • Data preparation: wrangling data
    • goals
      • wrangle our data
      • obtain numerical summaries of our data
    • key functions
      • arrange() our data in a meaningful order
      • subset the data to only filter() the rows and select() the columns of interest
      • mutate() existing variables and define new variables
      • summarize() various aspects of a variable, both overall and by group (group_by())
      • count() up the number of instances of an outcome or set of outcomes


  • Data preparation: reshaping data
    • goal: reshape our data to fit the task at hand
    • functions: - pivot_longer() - pivot_wider()


  • Data preparation: joining data
    • goal: join different datasets into one
    • functions
      • mutating joins which combine columns of different datasets: left_join(), inner_join(), full_join()
      • filtering joins which filter rows according to membership / non-membership in another dataset: semi_join(), anti_join()


  • Data preparation: working with factor variables
    • goals:
      • turn character variables into factor variables (when necessary)
      • turn factor variables into more meaningful factor variables
    • key functions:
      • reordering categories / levels: fct_relevel(), fct_reorder()
      • change category labels: fct_recode()


  • Data preparation: working with strings
    • goal: detect, replace, or extract certain patterns from character strings
    • key functions: - return a modified string: str_replace(), str_replace_all(), str_to_lower(), str_sub(), str_extract() - return a set of TRUE/FALSE: str_detect() - return a number: str_length()

We’ll practice SOME of these concepts today. Important caveats:

  • This activity is NOT an exhaustive review – it doesn’t cover every topic or every type of question you’ll be asked.
  • Be kind to yourself! If you haven’t started studying / reviewing yet, this might feel bumpy.





14.2 Part 1: What’s the verb? Game!

Goal: Review some of the functions we’ve learned.

Directions:

  • In your table group, take turns writing the answer on the Part 1 activity.
  • Switch every question.
  • If you are the one writing, you cannot say the answer but could guide others in your group.
  • This structure is intended to support your learning and establish equity in the group.

You’ll have 15 minutes to complete this activity, and we’ll review it together afterwards.





14.3 Part 2: Quiz practice

Goal: Practice some problems that are more in the style of the quiz questions. These give you a sense of the structure, vibe, and types of questions that might be asked so that none of that comes as a surprise.

Directions:

  • In your table group, take turns writing the answer on the Part 2 activity.
  • Switch every question.
  • If you are the one writing, you cannot say the answer but could guide others in your group.
  • This structure is intended to support your learning and establish equity in the group.

Once you’ve completed your work, work on Homework 6 (or anything else related to this class).





14.4 Wrap-up

  • Homework 6 is due 4/2.

  • Quiz 2 is next Tuesday in class.