---
title: "Lecture 12"
author: "Matt Blackwell"
date: "2023-10-12"
output: pdf_document
---

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

## Pivot longer


```{r}
library(tidyverse)
library(gov50data)
mortality

```



```{r}
mortality_long <- mortality |> 
  pivot_longer(
    cols = `1972`:`2020`,
    names_to = "year",
    values_to = "child_mortality"
  ) |>
  mutate(year = as.integer(year))
mortality_long
```

```{r}
mortality |> 
  pivot_longer(
    cols = `1972`:`2020`,
    names_to = "year",
    values_to = "child_mortality"
  ) |>
  mutate(year = as.integer(year)) |>
  ggplot(mapping = aes(x = year, y = child_mortality, group = country)) +
  geom_line(alpha = 0.25)
```






## Spotify


```{r}
spotify
```



```{r}
spotify |> 
  filter(!is.na(week1)) |>
  pivot_longer(
    cols = week1:week52, ## alternative: c(-`Track Name`, -Artist)
    names_to = "week_of_year",
    values_to = "rank", 
    names_prefix = "week"
  ) |>
  mutate(week_of_year = as.integer(week_of_year)) |> 
  ggplot(mapping = aes(x = week_of_year, y = rank, group = `Track Name`)) +
  geom_line(alpha = 0.25) +
  scale_y_reverse()
```

## Joins


```{r}
library(gapminder)

gapminder |> 
  count(country, year) |>
  filter(n > 1)
```


```{r}
mortality_long |>
  count(country, year) |>
  filter(n > 1)
```


```{r}
left_join(gapminder, mortality_long) |>
  select(country, year, lifeExp, pop, child_mortality)
```


```{r}
gapminder |> 
  inner_join(mortality_long)

```



```{r}
library(nycflights13)
flights2 <- flights |>
  select(year, time_hour, origin, dest, tailnum, carrier)
flights2
```


```{r}
planes2 <- planes |>
  select(tailnum, year, type, engine, seats)
planes2
```


```{r}
flights2 |>
  left_join(planes2, by = "tailnum") |>
  rename(year_built = year.y)

```


```{r}
flights2 |> 
  left_join(planes2 |> rename(year_built = year))

```