HW 4: Data Types

Due by 11:59 PM on Sunday, April 4, 2021

Instructions

  • Download the .Rmd template used for this homework here
  • After completing the questions, upload both the .RMD and .pdf OR .HTML files to Canvas.
  • Use tidyverse functions wherever possible.

Grading Rubric

Question.Part: Points Topic
1.1 1 Load data using correct function and a relative path
1.2a 1.5 Fix 5 factors
1.2b 1.5 Fix CrimeDate and CrimeTime
1.3 1 Fix variable names
1.4 1 Fix duplicate rows
1.5a 1 Find unique levels
1.5b 1.5 Correct forcats function
1.6 1.5 Correct lubridate extraction function
1.7a 1 Correct ggplot aes()
1.7b 1 Correct geom and arguments
1.7c 1 Correct orientation and faceting
1.7d 1 Reasonable explanation
1.8a 1.5 Correct factor reordering
1.8b 1 Production ready plot
1.9a 1 Correct Filtering
1.9b 1.5 Correct day of week extraction with labels
1.9c 1 Correct order
Total 20

Baltimore City Crime Data:

  1. Download the Baltimore City Crime dataset: baltimore_crime.csv. This data was originally available at this URL, but it has since been moved. Use a readr function to load the data.

  2. Review the data and fix variable types.

    • Make sure you convert CrimeCode, Description, Inside/Outside, Weapon, and District each to factors,
      • You can change col_types in your read_csv() function and / or using mutate().
    • Parse CrimeDate and CrimeTime into date and time (or period) objects using lubridate functions.
    • hint: There will be parse failure dialogue if you didn’t declare quiet = TRUE. That’s okay.

  3. Fix non-standard variable names

    • Use a “_” to replace the “/” or " " in the three non-standard variable names
    • Show the new names of the dataframe columns

  4. Fix duplicate rows

    • Are there any duplicate rows?
    • Remove them from the current data frame

  5. Fix different codings for variables

    • Find the unique levels for Inside_Outside.
      • It appears there are two different coding systems in place.
    • Use a forcats function to update the data frame to use a single coding system with the values Inside, Outside, and NA.
    • hint: there is more than one option here, but it may help to think about renaming or collapsing the levels

  6. Find the hour of each crime

    • From the CrimeDateTime variable, create a new variable called CrimeHour with the extracted hour that the crime occurred.

  7. Reproduce the following plot. (hint: geom_histogram())

    • By looking at it, which hour of the day has the most inside crime and which has the most outside crime.
    • Think about how data might get entered and speculate on the cause for the mid-day spike

  8. Reorder the Description variable by total frequency of occurrence. Create a presentation-ready plot that shows the Description on one axis and the count of occurrences on the other axis.

  9. Which days of the week has the most homicides in Baltimore? list all 7 labeled days in descending order by count.

Last updated on March 29, 2021

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