Data Rectangling

Talk about data rectangling and list-columns at RStudio Conf 2018 in San Diego
https://www.rstudio.com/conference/
Gist of code I showed:
https://gist.github.com/jennybc/3afafce0a06fde314b5c9844912d6bd7

Transcript

1. Data Wrangling @JennyBryan @jennybc  
2. Data Wrangling @JennyBryan @jennybc   Rect
6. atomic vectors logical factor integer, double
7. vectors of same length? DATA FRAME!
8. vectors don’t have to be atomic works for lists too! list column
9. name
 <chr> stuff
 <list> this is a data frame! a tibble, specifically
10. a list
11. a homogeneous list
12. Why work with lists? You have no choice. •String processing, e.g., splitting •JSON or XML, e.g. web APIs •Models, plots, & collections thereof
13. An API Of Ice And Fire https://anapioficeandfire.com https://cran.r-project.org/package=repurrrsive
14. "Combines the excitement of iris and mtcars, with the complexity of recursive lists. W00t!" install.packages("repurrrsive")
15. https://blog.rstudio.com/2017/08/22/rstudio-v1-1-preview-object-explorer/ View(YOUR_HAIRY_LIST)
16. got_chars[[9]][["name"]] got_chars[[9]][["titles"]]
17. x[[i]] x[i] x from http://r4ds.had.co.nz/vectors.html#lists-of-condiments
18. http://blog.codinghorror.com/falling-into-the-pit-o pit of success
19. https://shibumo.wordpress.com gentle hill of striving
21. map(.x, .f, ...) purrr::
22. map(.x, .f, ...) for every element of .x apply .f
23. map(.x, .f, ...) .f has some special shortcuts to make common tasks easy map(.x, "TEXT") map(.x, i)
24. .x = minis
25. map(minis, "pants")
26. go to R
27. map_lgl(.x, .f, ...) map_int(.x, .f, ...) map_dbl(.x, .f, ...) map_chr(.x, .f, ...)
28. map_dfr(minis, `[`, c("pants", "torso", "head")
29. If everything is equally easy, everything is equally hard. paraphrasing David Heinemeier Hansson re: Ruby on Rails
30. map(.x, .f, ...) .f can take many forms • existing function • anonymous function • formula
31. .x = minis
32. map(minis, antennate)
33. library(glue) 
 
 glue_data(
 list(name = "Jenny", born = "in Atlanta"),
 "{name} was born {born}."
 )
 #> Jenny was born in Atlanta. 
 
 glue_data(got_chars[[2]], "{name} was born {born}.")
 #> Tyrion Lannister was born In 273 AC, at Casterly Rock. 
 glue_data(got_chars[[9]], "{name} was born {born}.")
 #> Daenerys Targaryen was born In 284 AC, at Dragonstone.
34. glue_data(got_chars[[9]], "{name} was born {born}.") ~ glue_data( .x , "{name} was born {born}.") replace your example with .x prefix with ~ to say "it's a formula!"
35. map_chr(got_chars, ~ glue_data(.x, "{name} was born {born}."))
 #> [1] "Theon Greyjoy was born In 278 AC or 279 AC, at Pyke." #> [2] "Tyrion Lannister was born In 273 AC, at Casterly Rock." #> [3] "Victarion Greyjoy was born In 268 AC or before, at Pyke." #> [4] "Will was born ." #> [5] "Areo Hotah was born In 257 AC or before, at Norvos." #> [6] "Chett was born At Hag's Mire." #> [7] "Cressen was born In 219 AC or 220 AC." #> [8] "Arianne Martell was born In 276 AC, at Sunspear." #> [9] "Daenerys Targaryen was born In 284 AC, at Dragonstone." drop-in to any member of the map_*() family
36. name
 <chr> stuff
 <list> this is a data frame! a tibble, specifically
37. Why put a list into a data frame? safety & convenience •Manage multiple vectors holistically •Use existing toolkit for filter, select, etc.
38. What happens in the data frame Stays in the data frame
39. last R example: list in a data frame = list-column
40. lists are part of life RStudio Object viewer helps tibbles are list-friendly map() functions help you compute on & simplify lists