V43_gganimate.Rmd

```{r include=FALSE}
knitr::opts_chunk$set(cache = T, warning = F, message = F, 
                      class.output = "output", out.width='100%', 
                      fig.asp = 0.5, fig.align = 'center')
```

## 產製圖表動畫

https://gist.github.com/rafapereirabr/0d68f7ccfc3af1680c4c8353cf9ab345

```{r include=FALSE}
library(tidyverse)
library(readxl)
options(scipen = 999)
```

R也有套工具可以產製圖表動畫，概念上就是沿著一條資料維度，把多張圖給疊在一起變成一個gif動畫。本例子即是把產假之薪的範例沿著時間軸做動畫。每個時間點都是當年各國產假支薪給付程度的地圖，但由於有19年的資料，所以可以把年代當成動畫的時間軸。

以下是清理資料的步驟，會彙整出國名、國家代碼（ISO3）、年、和給付等級四個變項。預期利用國名、國家代碼和給付等級就可以畫出每年的圖。然後將年作為動畫的時間軸，便可產生地圖動畫。

```{r ani-prepare-data}
pml <- read_excel("data/WORLD-MACHE_Gender_6.8.15.xls", "Sheet1", col_names=T) %>%
	select(country, iso3, contains("matleave"), -contains("wrr")) %>%
	gather("year", "degree", 3:21) %>%
	replace_na(list(degree=0)) %>%
	mutate(year2=as.POSIXct(strptime(year, "matleave_%y"))) %>%
	mutate(year3 = strftime(year2, "%Y")) %>%
    select(country, ISO3=iso3, year=year3, degree)
```


### 地圖下載與轉換投影方法

此為下載地圖並處理地圖成為可以用`geom_polygom()`繪圖的多邊形資料點。

```{r ani-get-worldmap}
library(rworldmap)
wmap <- getMap(resolution="low")
wmap <- spTransform(wmap, CRS("+proj=robin")) # reproject
wmap <- fortify(wmap)
wmap %>%
    filter(!duplicated(id)) %>% head(10)
```


```{r ani-join-map-data}
pml_map <- wmap %>%
    left_join(pml, by=c("id"="country")) %>%
    filter(!is.na(ISO3)) %>%
    mutate(year = as.integer(year))

# devtools::install_github("thomasp85/transformr")

pml_map %>%
    select(id) %>%
    filter(!duplicated(.)) %>% head(10)
```

### 靜態繪圖測試

```{r ani-plot-testing}
pml_map %>%
    filter(year==1995) %>%
    ggplot() + 
    aes(x = long, y = lat, 
                     group=group, fill=factor(degree)) + 
    geom_polygon(color="grey") +
    theme_void() + 
    scale_fill_manual(values=c("1"="red",
                               "2"="LightCyan",
                               "3"="lightskyblue",
                               "4"="DodgerBlue",
                               "5"="MediumBlue")) + 
    coord_cartesian(xlim = c(-11807982, 14807978))
```

在採用gganimate繪圖時，僅需要多加一個動畫繪圖函式`+ transition_time(year)`即可，其他繪圖部分並無修改。最後才用`animate()`函式把這整個繪圖指令轉製為動畫，包含指定`fps`（frame per second）和長寬等參數。

```{r ani-animating}
library(gganimate)
pml.ani <- pml_map %>%
    ggplot() + 
    aes(x = long, y = lat, 
        group=group, fill=factor(degree)) + 
    geom_polygon(color="grey") +
    theme_void() + 
    scale_fill_manual(values=c("1"="red",
                               "2"="LightCyan",
                               "3"="lightskyblue",
                               "4"="DodgerBlue",
                               "5"="MediumBlue")) + 
    coord_cartesian(xlim = c(-11807982, 14807978)) + 
    transition_time(year)
# + 
#     ease_aes("linear") +
#     enter_fade() +
#     exit_fade()

animate(pml.ani, fps = 10, end_pause = 30, width = 750, height = 450, renderer = gifski_renderer())

anim_save("jour5014/pml2.gif", animation = last_animation())
```

```{r}
knitr::include_graphics("jour5014/pml2.gif")
```