## ----setup, include = FALSE---------------------------------------------------
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

## -----------------------------------------------------------------------------
library(tibble)
library(dplyr)
library(tidyr)
library(purrr)
library(ggplot2)

diamonds

## -----------------------------------------------------------------------------
ggplot(diamonds) +
  geom_histogram(aes(x = price, y = stat(count)))

ggplot(diamonds) +
  geom_histogram(aes(x = price, y = stat(count))) +
  scale_x_log10()

## -----------------------------------------------------------------------------
ggplot(diamonds) +
  geom_histogram(aes(x = price, y = stat(count))) +
  facet_wrap(vars(cut), ncol = 1) +
  scale_x_log10() +
  ggtitle("Price vs. cut")

ggplot(diamonds) +
  geom_histogram(aes(x = price, y = stat(count))) +
  facet_wrap(vars(color), ncol = 1) +
  scale_x_log10() +
  ggtitle("Price vs. color")


## -----------------------------------------------------------------------------
diamonds %>% split(diamonds$cut)

## -----------------------------------------------------------------------------
diamonds %>%
  split(diamonds$cut) %>%
  map_dbl(~ mean(.$price))

## -----------------------------------------------------------------------------
diamonds_list <- diamonds %>% split(list(diamonds$cut, diamonds$color))

map_dbl(diamonds_list, ~ mean(.$price))
map_dbl(diamonds_list, ~ cor(.$price, .$depth))

## -----------------------------------------------------------------------------
nested_diamonds <-
  diamonds %>%
  select(cut, color, clarity, depth, price) %>%
  nest(data = c(clarity, depth, price))

nested_diamonds

## -----------------------------------------------------------------------------
nested_diamonds$data[[1]]

nested_diamonds$data[[2]]

## -----------------------------------------------------------------------------
nested_diamonds %>%
  mutate(
    mean_price     = map_dbl(data, ~ mean(.$price)),
    pricedepth_cor = map_dbl(data, ~ cor(.$price, .$depth)))

## -----------------------------------------------------------------------------
diamonds_models <-
  nested_diamonds %>%
  mutate(
    price_mod     = map(data, ~ lm(.$price ~ .$depth)),
    price_summary = map(price_mod, summary),
    price_rsq     = map_dbl(price_summary, "r.squared"))

diamonds_models

## ---- eval=FALSE--------------------------------------------------------------
#  # sabotage a group by removing all its rows
#  nested_diamonds$data[[5]] <-
#    nested_diamonds$data[[5]] %>%
#    filter(price < 300)
#  
#  # now attempt to calculate summary statistics
#  diamonds_models =
#    nested_diamonds %>%
#    mutate(
#      price_mod = map(data, ~ lm(.$price ~ .$depth)),
#      price_summary = map(price_mod, summary),
#      price_rsq = map_dbl(price_summary, "r.squared"))
#  
#  diamonds_models
#  #> Error in mutate_impl(.data, dots) : Evaluation error: 0 (non-NA) cases.

## -----------------------------------------------------------------------------
safe_lm <- safely(lm)

purrr_models <-
  nested_diamonds %>%
  mutate(price_mod = map(data, ~ safe_lm(.$price ~ .$depth)))

purrr_models

## -----------------------------------------------------------------------------
purrr_models$price_mod[[1]]

purrr_models$price_mod[[5]]

purrr_models %>% mutate(mod_result = map(price_mod, "result"))

## -----------------------------------------------------------------------------
library(collateral)

nested_diamonds$data[[5]] <- nested_diamonds$data[[5]] %>% filter(price < 300)

collat_models <-
  nested_diamonds %>%
  mutate(price_mod = map_peacefully(data, ~ lm(.x$price ~ .x$depth)))

print(collat_models)

## -----------------------------------------------------------------------------
collat_models %>%
  mutate(
    # this returns a list of `lm` objects
    mod_result = map(price_mod, "result"),
    # this returns a character vector
    mod_error = map_chr(price_mod, c("error", "message"), .null = NA))

## -----------------------------------------------------------------------------
summary(collat_models$price_mod) 

## -----------------------------------------------------------------------------
collat_models %>%
  group_by(color) %>%
  summarise(
    n_res = tally_results(price_mod),
    n_err = tally_errors(price_mod))
    
collat_models %>%
  filter(has_errors(price_mod))

collat_models %>%
  filter(!has_results(price_mod))