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Data Wrangling @JennyBryan @jennybc  

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Data Wrangling @JennyBryan @jennybc   Rect

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atomic vectors logical factor integer, double

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vectors of same length? DATA FRAME!

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vectors don’t have to be atomic works for lists too! list column

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name
 stuff
 this is a data frame! a tibble, specifically

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a list

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a homogeneous list

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Why work with lists? You have no choice. •String processing, e.g., splitting •JSON or XML, e.g. web APIs •Models, plots, & collections thereof

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An API Of Ice And Fire https://anapioficeandfire.com https://cran.r-project.org/package=repurrrsive

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"Combines the excitement of iris and mtcars, with the complexity of recursive lists. W00t!" install.packages("repurrrsive")

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https://blog.rstudio.com/2017/08/22/rstudio-v1-1-preview-object-explorer/ View(YOUR_HAIRY_LIST)

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got_chars[[9]][["name"]] got_chars[[9]][["titles"]]

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x[[i]] x[i] x from http://r4ds.had.co.nz/vectors.html#lists-of-condiments

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http://blog.codinghorror.com/falling-into-the-pit-o pit of success

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https://shibumo.wordpress.com gentle hill of striving

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map(.x, .f, ...) purrr::

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map(.x, .f, ...) for every element of .x apply .f

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map(.x, .f, ...) .f has some special shortcuts to make common tasks easy map(.x, "TEXT") map(.x, i)

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.x = minis

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map(minis, "pants")

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go to R

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map_lgl(.x, .f, ...) map_int(.x, .f, ...) map_dbl(.x, .f, ...) map_chr(.x, .f, ...)

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map_dfr(minis, `[`, c("pants", "torso", "head")

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If everything is equally easy, everything is equally hard. paraphrasing David Heinemeier Hansson re: Ruby on Rails

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map(.x, .f, ...) .f can take many forms • existing function • anonymous function • formula

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.x = minis

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map(minis, antennate)

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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.

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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!"

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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

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name
 stuff
 this is a data frame! a tibble, specifically

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Why put a list into a data frame? safety & convenience •Manage multiple vectors holistically •Use existing toolkit for filter, select, etc.

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What happens in the data frame Stays in the data frame

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last R example: list in a data frame = list-column

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lists are part of life RStudio Object viewer helps tibbles are list-friendly map() functions help you compute on & simplify lists