9/9/2022

Problem session for Activity 4 and HW#1

• Volunteers will drop their solutions into !Student R Code - Solutions for Activities and Exercises on our Google Drive folder. Please title them HW1Exercise#-yourname.pdf and HW1Exercise#-yourname.R.

Chapter 4 - Data Wrangling on one table- see DataWrangling1.R on our Google Drive folder

• A grammar for data wrangling (dplyr package)
  • select() - take a subset of the columns
  • filter() - take a subset of the rows
  • mutate() - add or modify existing columns
  • arrange() - sort the rows
  • summarize() - aggregate the data across rows (e.g., group it according to some criteria)
• There are lots of ways to slice-and-dice a single table of data
• dplyr is related to SQL (a relational database querying syntax) and OLAP (online analytical processing) hypercube
• Chapters 15 and 16 provide many more details on SQL

Activity 5 - we will have a PS on Monday

• Replicate the data wrangling used in the extended example of Ben Baumer's time with the NY Mets. You can also change to a team of your choice. For example, I would use the Baltimore Orioles!

Please read Chapter 5 for class on Monday.