Chapter_21.Rmd

---
title: "Chapter 21"
author: "Laura"
date: "12/15/2019"
output: html_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE, cache = TRUE)

library(tidyverse); library(skimr); library(nycflights13); library(GGally); library(ggstance); library(lvplot); library(hexbin); library(modelr); library(magrittr); library(stringr); library(htmlwidgets); library(forcats);  library(lubridate); #library(maps); library(mapproj);

```

## Notes for Chapter 21: Iteration

```{r}
mtcars %>% 
  split(.$cyl) %>% 
  map(~ lm(mpg ~ wt, data = .x))

map(1:5, runif)

# from primer
nested_gapminder <-  gapminder %>%
  group_by(country) %>%
  nest()

nested_gapminder %>%
  pluck("data") %>%
  pluck(1)

nested_gapminder %>%  
  pluck("data") %>%
  map(~ lm(lifeExp ~ year, data = .))

gap_models <-  nested_gapminder %>%
  mutate(models = map(data, ~ lm(lifeExp ~ year, data = .x)))

gap_coefs <- gap_models %>%
  mutate(coefficient = map_dbl(models, ~ coef(.x) %>% pluck("year")))

gap_coefs %>%
  mutate(r_squared = map_dbl(models, ~ summary(.x) %>% pluck("r.squared")))


```